change the serialized souper format a bit as suggested by Peter in email:
annotate each block with its number of predecessors; this simplifies parsing a
bit
oops this slipped through my earlier patch to remove isTriviallyInvalid
Merge pull request #109 from regehr/blockpred

change the serialized souper format a bit as suggested by Peter in email
Merge pull request #113 from regehr/cleanup-triviallyinvalid

oops this slipped through my earlier patch to remove isTriviallyInvalid
changes suggested by Yang
Merge remote-tracking branch 'origin/master' into printcontext

Conflicts:
	lib/Inst/Inst.cpp
	lib/Parser/Parser.cpp