Make firmware switchable between 1.0 and 2.0

[buserp]

The T-Tree firmware currently supports only the T-Tree 2.0. Adding a command-line flag or way to switch between 1.0 and 2.0 would make it more backwards-compatible.

The main difference is that the T-Tree 1.0 doesn't have the external user interface, so is a strict subset of functionality of the T-Tree 2.0.