Add constructor for Func wrapper from Function

Func contains all the logic for transforming a schedule, so it is useful to be
able to reconstitute a Func handle directly from a Function dug, e.g., out of
the call graph of Functions.
Fix for LLVM api change
Inline reductions optionally take the RDom that they reduce over

This lets you reference multiple RDoms inside them. Only the named one
gets captured.
Added test for bounds inference on function values.
Taught bounds inference about ceil, floor, round.

Partially fixes #199
Add visit_function helper to IRVisitor

This function applies an IRVisitor to all Exprs in a Function
definition, including update definitions, update index args,
and the extents of referenced RDoms.
Merge branch 'master' of github.com:halide/Halide
Remove sources of undefined order of evaluation in CodeGen_C

Fixes #239
Merge branch 'master' of github.com:halide/Halide
Add IRDeepVisitor
Fix IRVisitor build for gcc/linux
Registered more tutorials with doxygen docs
add pnacl_math to cmake build
New llvm syntax for DataLayout pass
Suppress data layout warnings in initial module
Remove roundf from test because windows
Handle LLVM API change in adding a pass to handle DataLayout.
Merge branch 'master' into test_gpu
NAming changes, add more uses of evaluate_may_gpu.