Adds efficient devectorization of explicit x[v] for vector v.
Allow for more general TGeneralRef1's, including logical indices.
Introduct TScalarRef1 to fix some test failures.
TScalarRef1 fixes.
An (unsuccessful) attempt to fix some test failures.

Almost feels like we should define setindex! on scalars.
Add tests for vector indexing.
Let size be general for TGeneralRef1.
Generalize EWiseMode{0}
Update tests.

A couple of EWiseMode switches. Also, update test_scalar_ref to use [1:end] syntax
rather than [1:].
Update test_texpr to use [1:end] syntax.
Fixes for [1:end] syntax.
Fix scalar() on general references.
Drop unnecessary size check in EWiseMode{1}.
Merge pull request #24 from blakejohnson/expand-indexing

WIP: Generate efficient codes for a larger class of references