Pcbnew: enhancements for blind/buried vias palcement, and save blind/buried vias allowed option in .kicad_pcb file

Minor code cleaning. Pcbnew: better iniatilization of members in DRAWSEGMENT, TRACK, EDGE_MOD (useful when using  python scripting).

Fix for locales that set , as a decimal point (which is incompatible with python scripting), also fixed the m_Reference encapsulation in module to Reference()

Footprint wizard converts from user units to internal units back and forth, so user can type in mm or mils now