Switch to linear.
Switch to linear.

Also switched to vector instead of array.
Half fix tests.
Use old active semantics.
Restrict Active and Dynamic to Rational.
Update tests.
UndecidableInstances for ghc < 7.7, update version, add 7.8.3 to travis.
cabal: conservative upper bound on linear
Merge pull request #7 from diagrams/linear

Use `linear` instead of `vector-space`