Lower dependency on base, to support GHC 7.x

Not 100% sure 7.2 / 7.0 work, but they ought to.
digging into renderTrail
Merge pull request #2 from mgsloan/master

Lower dependency on base, to support GHC 7.x
merge
Merge branch 'master' of github.com:ku-fpg/diagrams-canvas
Merge branch 'jeffreyrosenbluth-master'
merge from jeffreyrosenbluth
Fixing ignores
merge with upstream/master