Document the main types
Add note about key deduplication
Update copyright and bug-reports fields
Add Data.BimapMany simple variant

without any extra values
Move BimapMany to BimapMany.Extended

in preparation to
* extending BimapMany.Extended
* creating a regular variant with no extra values
Split utils into internal module
Add test for stray empty sets
Add reference to bimap
gitignore cabal.project.local~
Add elems* and keys* functions
Lazy/strict Functor and Traversable instances
Cabal file improvements
Add description, readme, and source-repository