compile base_screen.cpp separately for {pcbnew,cvpcb} and eeschema, so we can diverge internal units at compile time, not runtime

Eeschema: add compil option in sch_field.cpp to go back to old behavior for field texts justifications (this option is not activated)
Note: only vertical texts have a modified behavior.
Minor other changes.

Remove obsolete foldr resources/icons.
Updates svg icons in folder resources.

Fix minor other issues.
Remove unused files.

Eeschema: optimize import of footprints names ( .stf files) that was time consumming with large designs.