[*] reorganize src/ subtree

This moves the fontloader files into a separate subdirectory to simplify
maintainance.
[scripts] adapt status file generator to dir structure
[build] include cleanup targets in makefile usage message
[fontloader] change prefix of imported files to “fontloader”
[scripts] adapt status script to reflect current fontloader file prefix
[*] update news
[build] include import script in makefile
[scripts] add early draft of import helper