* Command definition now uses char * instead of String
* registered_commands is now an array of pointers to Commands,
previously this was an array of Command and was allocated to
MAX_COMMANDS entries which were then overwritten with the module
provided Commands, so every Command used twice as much memory. This
saves ~200bytes
* Several (u)ints are now (u)int8_t
On the nano with all modules included this reduces global RAM use from
1676 bytes to 1237 bytes (from 81.8% to 60.4%).
- Added endstop and light_sensor module
- Improved configuration by splitting wiring configs to boards.h
- Added a unit test for argument parsing
- Fixed many smaller bugs
