Mentioned in #451, I'd like to look at the possibility of moving a large portion of the

#ifdef FEATURE_ENABLE
  #include "feature.h"
  feature();
#endif

code blocks to having a wrapper on the entire feature.c file to disable it, and include dummy functions where necessary (they likely won't be needed that often).

Pros:

• disable via config.h instead of Makefile (doesn't really cleaning, easier/more straight-forward to modify, all being c)
• cleaner code, no giant #ifdefs around calls (something action.c is suffering from)
• no #ifdefs required in keymap.c

Cons:

• is the compiler smart enough to exclude things without affecting memory size?
• code is less clear, since functions will always be called (unsure if they're doing anything)
• feature.c will always be compiled (I believe) - does this have an effect on compile time?

Comments are welcome!