MSA

- add a menu button to the app to provide for devices without a physical method of opening the menu.
- improve scanner detection to include both portrait and landscape
- remove two step stocktake line searching by optimizing process
- handle IMEI/SerialNo pairs correctly in all scenarios.
- 2016 version specific changes
- non-serialised scan-counting for both camera and external scanners
- option to both "add to" and "overwrite" the value of a non-serialised stocktake item count.