Fixed linear kernel.
Fix a couple warnings in test code. Both were unlikely to cause
visible bugs, but it is a bit cleaner now.
Add a test to cover the bug that was fixed recently where bool in
memory is a byte, but a bool vector inside llvm is bitpacked so
loading 8 bools would load a byte, not 8-bytes, if vectorized.
Merge branch 'master' of github.com:halide/Halide
White space cleanup.
Had this under two names. Delete the less descriptive one.
llvm trunk removed arm neon fabs intrinsic
Merge branch 'master' of github.com:halide/Halide
Fix definededness test in merge_boxes
Bounds inference now also tracks bounds on the *value* of each function.

Only applies to pure functions. Useful for warping and other indirection.
Allow unbounded boxes in box touched of letstmt
Handle vectorized trace ids
Removed some != NULL
Removed many of the variants of box_touched
Test is no longer relevant, and in fact misleading.
Added print and print_when functions for debugging.

Required a strict expr if_then_else intrinsic, which may be useful later.

Also required an equivalent of the comma operator (evaluate two things,
return one of them). Made it an intrinsic called "return_second".