Limit exports from OpenGL backend
bump upper limit on containers
.gitignore
set display modes
Support non-convex polygons, clipping paths, line form styles, transparency

Uses GLU tesselate function to handle:
    - non-convex polygons
    - self-intersecting polygons
    - fill rules
    - clipping

Converts lines to polygons to support line forms:
    - dashed lines
    - LineCap Attribute
    - LineJoin Attribute

The State Monad is used to allow the final geometry to depend on the
Style.  The state is therefore cleared after each primitive.  Because
the polygons representing lines also need to be clipped, nearly all
the style information needs to be available in the State.  Because a
Path with multiple Trails is handled differently from several
one-Trail Paths, GLU tesselate needs to be called before flattening to
GlPrims.

closes https://github.com/bergey/diagrams-opengl/pull/1
Add Haddock comments to the type signatures of the line form functions
Add mtl to cabal; needed for State Monad
Rename variables to silence GHC warnings

- (p0,p1) instead of (p1,p2)
- add underscore to fc, lc, lw
- avoid deprecated colorToRGBA

Conflicts:
	src/Diagrams/Backend/OpenGL.hs
Tighten up definition of tessRegion
Only specify GL. where ambiguous

Import Diagrams, Colour, OpenGL unqualified but with a short name
Add several examples / test cases, mostly for features added in ccb033ed

These examples come from the manual:
- fillRule
- transparency
- lineForm

In addition:
- Add unfilled example to fillRule.hs
- add path-superposition example to fillRule.hs
- Expand lines test case to test path closing