o added a notation field to Theory
o encapsulated the parameters of the various expression parsing routines into a monad called Parser
Now the command \with{theory} allows the use of 'theory' in the current machine
o Removed dependency on Theories.Notation: notations are now built on the fly
o optimized the creation of parsing table (using topological sort instead of Floyd's algorithm)
o introduced the parsing tables as part of the state of the parser (System) to minimize their recomputation
o System now has a map of theories as well as a map of machines ... architecture to come