Implemented and tested for both platforms. This is quite a big
commit. Unlike with the previous changes to now choosable PWM
frequencies, all board configuration files and Configtool had
to be changed immediately to deal with the additional parameter
in DEFINE_HEATER() and keep AVR builds working (and regression
tests passing).
Validation is no longer required, as we now validate in the
creation dialog already. And coloring one item in a two-item list
almost looks like this item were highlighted.
Markus Hitter
jbernardis