cleanup : removed prefixed module names
Make P and L parameters to IncidencePlane module
Another major rewrite with more lemmas added

- reverse of irred chain is irred
- reverse preserves length
- make incidence proof in chain constructor irrelavant
- make parts of irreducible predicate irrelavent

Added a misc module with general proofs, for example those related to
the natural numbers
Introduce axioms for generalized polygon