FIELD Ordering system and method applicable to food and beverage retail premises such as restaurants, bars, cafes, hotels, food courts, canteens, hospitals, and any such premises, whether public, private/restricted, fixed location or mobile (e.g. food carts/vans, aeroplanes), where consumers can order food and beverage the supply of which must be appropriately accounted and paid for by the consumer or otherwise allocated. BACKGROUND [0001] There are several known methods for consumer ordering of food and beverage while at a food and beverage retail premises. A basic technique is for consumers to visit the counter to place an order and a staff member will enter the order into a point of sale (POS) system. [0002] In modification to this technique, consumers may be seated first and served by a staff member who will take their order, which is either committed to their memory or written down, until they return to the counter to enter the order into the POS. [0003] In modification to technique 0002, staff may use a venue-owned or leased wireless network device to enter an order directly into the POS. [0004] In modification to technique 0003, consumers may be empowered to place their own order using a venue-owned or leased wireless network device that sends the order directly into the POS or to a separate printer. [0005] In modification to technique 0004, consumers may use their own personal wireless network device to request authorisation from the food retail premises to place an order, which is then displayed on screen at the premises (refer patent application no. AU 2012100373 A4). [0006] In all known on-premises ordering techniques described above, payment may be pre- or post-consumption of food and beverage, and is made by cash or credit card at the POS or via a venue-owned or leased mobile electronic funds transfer (EFT) device. It is known that some food and retail premises accept loyalty cards in lieu of payment, or allow regular consumers (either individuals or affiliated with a business for example) to order "on account" which will be settled at a later time, e.g. on a monthly basis. SUMMARY OF INVENTION PROBLEM: [0007] In general, food and beverage retail premises such as restaurants employ staff to take orders from consumers (either at their table or over the counter), enter the orders into a point-of-sale (POS) system, process payment (typically cash or credit card either at the time that the order is placed or after the product is consumed and before the consumer leaves the premises), and fulfill the order by preparing and serving the requested items to the consumer. 1 [0008] The known techniques described require staff at one or more points of the ordering process and all require staff to take payment. Requiring staff has costs to the retail business, causes delays when demand for staff time is greater than that available (e.g. waiting for staff to be available to take orders, process payment, serve tables, etc.), and causes delays when a bottle-neck in the process exists, e.g. consumers queuing to order. [0009] Where payment is accepted post-consumption of food and beverage, the known techniques described also risk consumers leaving the premises without paying for their order. SOLUTION: [0010] A computer software system (including application, smart phone app, web app, web site, etc.) that allows consumers to use their personal computing devices (e.g. smart phone, laptop, tablet, etc.) to order and pay for food and beverage from the retail premises at which they are visiting. [0011] Using their personal computing device, consumers will connect to the network (e.g. LAN, WAN, telecommunications tower, etc.). Wherever possible, the software will use geolocation to identify at which premises the consumer is currently located. Alternatively, the consumer may choose or search for their location from a list. The consumer can then browse and search the food and beverage menu, choose which items they would like to purchase, optionally customise these items, specify preferred payment method (pre- or post-consumption), enter payment details (e.g. credit card), specify their table number or other location identifier (e.g. table name, table location or to takeaway, etc.), optionally add a note or special instruction to their order, and then submit the order to the premises for fulfilment. [0012] The order will first be sent to a web server hosting our proprietary software and database, where it is validated and stored. Payment is also processed or pre-authorised at this point. [0013] The order will then be retrieved from the database by our software at the venue. This software can be used on any networked computing device, typically a POS terminal or back-office computer. The software will check for new orders at regular intervals, e.g. every 15 seconds without the need for additional venue hardware or equipment. [0014] Once an order is retrieved it can be passed onto the POS system for distribution to kitchen and/or other staff in its usual/configured manner (e.g. receipt printer, kitchen video display, etc.), or sent directly to a receipt printer or screen display. 0015] When the order is ready a signal can be sent to the consumer's portable networked device e.g. smartphone. [0016] Where customers have opted to post-pay, they may again use their personal computing device to close the table, leave a monetary tip, and confirm that payment can now be processed. In the event that no further orders are processed against the consumers account, on their table, within a venue-specified time-frame, e.g. no additional food or beverage within 60 minutes of the original order, then the system will automatically close 2 the table and process the consumer's payment method for the order total. ADVANTAGEOUS EFFECTS: [0017] Consumer can order from the comfort of any chosen location in the premises without having to attend and order point, queuing or interacting with staff if he/she so wishes. 0018] Consumer can pay without waiting for staff to issue an account at the end of the on-premise experience and can consequently leave the premises after eating without the usual frustrating delay to get a "check" and pay the bill. 0019] Using this computer software system eliminates the requirement for staff to be available for the purposes of taking orders from consumers, entering orders into the P.O.S. system, and processing payment. 0020] The consumer device's "ready" signal eliminates the venue's need for costly buzzer systems which require charging, maintenance and get lost. [0021] The risk of consumers leaving the premises without paying for their order is also eliminated, as payment details are obtained at the time of order. [0022] This computer software system can be used stand-alone by the food and beverage retailers, or in addition to their existing methods of order and payment processing. In cases where it is integrated with, or used alongside, an existing POS then no additional computer hardware is required on the retailer's part. BRIEF DESCRIPTION OF DRAWINGS Figure 1: Overview of software communication between (1) consumer-owned personal computing device, (2) our servers, (3) our software on premises. Figure 2: Overview of the processes involved in submitting an order through the system, as described in solution, paragraphs 0011 to 0012. Figure 3: Overview of the processes involved in retrieving a new order from the system, as described in solution, paragraphs 0013 to 0014. 3