When we create a new wuclass, show the option to decide the platform or common if it does not depend on hardware.

[wycc]

• Doing this using the UI would lead to platform specific code ending up in the /lib/wkpf/c/common directory. When writing C code, we should have some mechanism to select a platform (currently posix/arduino. later maybe also taroko or others). If the wuclass doesn’t depend on hardware, it should be possible to put the code in the common directory, but in this case there can’t be any code for the same wuclass in any of the platform specific directories.