* Add drag context menu entry for junctions that actually form a junction
  with wires to EESchema.
* Add function to test for junctions to SCH_COLLECTOR class.
* Create annotate type and sort order enums to eliminate magic numbers
  used in annotate code.
* Remove duplicate Doxygen comments from annotate.cpp and improve the
  actual Doxygen comments in wxEeschemaStruct.h.