allow `free-4.6`
Change test to a cabal test-suite

This way (1) the tests can be run with 'cabal test', and (2) users do
not have to install the tests and all its dependencies by default.
Bumping FontyFruity dep
Fixing transparency in gradient, fix #11
Adding some comments for the modulable type class.
Merge pull request #10 from byorgey/master

A couple tweaks
Adding radial gradient test with opacity
Adding real testing of alpha composition.
Fixing alpha blending on top of translucent background, fix #13
Bumping changelog
Merge branch 'master' into release

Conflicts:
	Rasterific.cabal