Look for styles and footprints also in /usr/share/pcbdraw/
Look for styles and footprints also in /usr/share/pcbdraw/

This decouples the scripts from their data.
Data can be installed in GLOBAL_DATA_DIR (/usr/share/pcbdraw/)
Footprints:
- In addition to use PKG_BASE for default libs now we also look on
  GLOBAL_DATA_DIR
Styles:
- We try in the current directory.
- Then we try to add '.json' extension and look again.
- Try in PKG_BASE
- Finally try with GLOBAL_DATA_DIR
The "builtin:" mechanism bypass the search and goes straight to
PKG_BASE

yaqwsx/PcbDraw,yaqwsx/PcbDraw