[PROJECT.py] some additions and minor changes to cmdline options

- new option (-L) to list all buildable programs (same option as in make.py)
- new option (-n xxx) to chose a program name instead only program id (-p yyy) as before  (same option as in make.py)
- new option (-c) to clean the export folder (similar to options in build.py and make.py which clean build folder)
- reorder the options similar to build.py and make.py when printing the help text
- order the entries in mcu and ide lists when printing the help text - perhaps the same can be done in the other tools?
Does clean need to exit ? Not just a clean and continue building ?