Add transformation rules for partial evaluation

Now when there is an application of something with a [static] argument,
a transformation rule is added for changing any other applications of
the same form to use the partially evaluated definition.

Transformation rules are not, however, implemented yet!
Merge branch 'master' of git://github.com/idris-lang/Idris-dev into partial-eval
Implement transformation rules

Now the partial evaluator, in its basic form, is working, recursively
generating any required definitions from [static] annotations.
Merge pull request #1582 from edwinb/partial-eval

Partial evaluation