Adding parallel glob iterator. This should be portable (tested both on linux and
mac).
git rid of two functions
Merge branch 'master' into parallel-glob
Merge branch 'master' into parallel-glob
Merge branch 'master' into parallel-glob
Merge branch 'master' into parallel-glob
Merge branch 'master' into parallel-glob
Merge branch 'master' into parallel-glob
Merge branch 'master' into parallel-glob
Small cleanup to pruneVisit functions

Instead of walking all ASTs and filtering for SymExprs or DefExprs, collect
SymExprs or DefExpers and walk over them directly.  Also replaced some Vecs
with std::vectors.
Merge branch 'master' into parallel-glob
Merge pull request #32 from tzakian/parallel-glob

Parallel glob iterator
Merge pull request #33 from daviditen/pruneVisitCleanup

Small cleanup to pruneVisit functions
[Reviewed by hildeth]