To use multiple working threads. This entailed adding KiCad typedefs:
*) Add typedefs for MUTEX and MUTLOCK which mask the actual choices for the project.
*) Add FOOTPRINT_LIST::DisplayErrors( wxWindow* ) which is a single strategy for
showing aggregated load errors. Although what's there is only scaffolding
and needs a volunteer who knows HTML pretty well.
*) Ensure all callers of ReadFootprintFiles() use the new DisplayErrors() function.
*) Push utf8.cpp and utf8.h into common library for open use.
Dick Hollenbeck