+ add an include file which contains common defines and a macro which allows changing the Graph unit
+ add include to all used units
* move other directives after the include directive, because the $mode switch might change them
* change the used graph unit from PtcGraph to GraphUnit, so that can be easily switched per platform
* change usage of F3 as terminate key to F5, as keys F1 to F4 seem to be problematic at least on my two Linux computers