allocator implies constant flags
remove origin & optimize merge (issue #75)
Merge branch 'master' into usable-rules

Conflicts:
	src/CO4/Allocator.hs
fixed version of JFP_Ex31.cpf.2

contains two additional rules in unlabProc
Merge branch 'patch-1' of https://github.com/rene-thiemann/co4 into usable-rules
fix unlabel proof (issue #88)
only use necessary assignments for each rule (issue #89)
Merge branch 'usable-rules' of https://github.com/jwaldmann/co4 into usable-rules
git-ignore more files (created by calling ghc directly)