== ToDo ==
* find a real fix  for cos 90 != 0 bug (only in double version of compile)

* get rid of dlabel.h & dlabel.cpp
* key groups for color configuration need to be rethought
* better to handle keys with "accel" or with "keyPressEvent"?

* think about either doing RichText by hand on labels, or only draw visible buttons, to enhance startup time.

Following examples from the handbook do not work anymore as explained
in the documentation. Need to update the documentation!!
* 22.345 Mod 8 =  will give the result 6.345
* 10.345 Lsh 3 = also gives 80
* 16 Inv Lsh 2 = gives 4 (16 divided by 2 twice).
* 16.999 Inv Lsh 2 = also gives 4