allow enabling/disabling certain features via define
Fix Leonardo bootloader enter.
Fix check for Leonardo bootloader enter. (one should not code when too tired)...
Merge branch 'master' into 20-standalone
Merge branch '20-standalone' into 21-bool
Merge branch '21-bool' into 22-printf

Conflicts:
	TX.h
Merge branch '22-printf' into 23-wiring
Merge branch '23-wiring' into 24-c-only