o reimplemented the operator parsing table as a sparse matrix
o changed the proof parser to delegate to tactics all the logic concerning the variable names, goals and hypotheses (hypotheses names are still handled by the parser but this should change soon)
o changed Theory so that theorems can have a proof attached.
Added names to hypotheses in sequents
Merge branch 'master' of https://github.com/cipher1024/literate-unitb

Conflicts:
	Document/expression.hs
	Document/machine.hs
	Document/proof.hs
	Logic/tactics.hs
	UnitB/po.hs
	last_result.txt
	result.txt
	utilities/graph.hs
Using the tactic monad to check the validity of assumptions