Include KLC checks in library editors (lp:#1803585)

Original report created by Antonio Vázquez Blanco (antoniovazquezblanco)

Currently librarians use python check scripts to allow Travis to perform a
rough check of wether a symbol or a footprint conforms with basic KLC
rules.

Kicad library editors include a "DRC" or similar button that would be
awesome if could include KLC checking.

The task would basically be porting the existing python code to KiCad to be
able to perform the checks directly in the tool.

That would make checking easier for library collaborators and would lead to
less work for librarians that are currently overwhelmed by the amounts of
contributions to review.

Original tags: drc eeschema erc pcbnew python