Added a simple wrapper
Moved Rule into its own file.
Moved ProdState into base
Move Grammar into Boar.Base
Moved the Generate package into the Boar package
Moved ProdState into Generate, as it's really only used for generation
And other changes
Move ParseState into Boar.Generate
Renamed State to ParseState, which is less ambiguous
Current state
Simplify ProdState
Add new ProdStateSet, as a partial replacement of ParseState (since it
isn't always a full state).
Added new stuff
Fixed up mergeable.

Changed the name of the containers module
Going to make a major change to containers