pidgin.h phase3: create pidgin.h and force its usage
fix the section id of pidgincore.h
Generate our pidgin.h file
Add include guard to all pidgin/*.h files and deal with the fallout from that.
Also had to namespace PIDGIN_BLIST_COLUMN_NAME, will come back and get the rest at a later time.
Testing Done:
Compile test, including some plugins that don't build by default. Also ran everything seems fine.
Reviewed at https://reviews.imfreedom.org/r/50/