e6 timer m4-inline-code conversion

*Motivation:* Upcoming changes to the meta-timer code require all timers to be callable C functions. Neither m4-inline-code nor cpp macros will work any more. Also timer functions will be called by reference, preventing the compiler from optimizing away calls to conditionally empty functions.

*Changes:* Converted timer code using m4-inline-code to C functions. Added proper dependencies handling via m4. Changed/Removed cpp macros.

This PR should have no impact on the functionality of e6.

@all: Adding proper m4 dependencies to the meta code block is really easy. CPP conditionals *do not work* with m4. Plz have a look at the existing code, there are many working examples.