A few methods differed by the number or type of arguments in derived
classes. They were changed to match the base class method signature and
marked as 'override'.
* Add footprint library table loading to footprint editor.
* Overload FOOTPRINT_INFO::ReadFootprintFiles() to read footprints from the
footprint library tables.
* Fix a bug in FP_LIB_TABLE::IsEmpty() when the table has a fallback table.
* Add code to FOOTPRINT_EDIT_FRAME to use footprint library tables.
* Add an optional build time version of PCB_EDIT_FRAME::loadFootprints() to
populate netlist footprints from footprint library table.
* Remove adding footprints to board whenever GetModuleLibrary() is called and
move loading locally as required.
* Add missing source file license comments and coding policy fixes.
Eldar Khayrullin
Maciej Suminski
Simon Richter
Wayne Stambaugh
jean-pierre charras
Alexander Lunef