Checkpoint GPU scheduling API changes and test updates.
Merge branch 'master' into test_gpu
Legacy cuda* calls are needed on ScheduleHandle as well.
Merge branch 'master' into test_gpu
Convert tests and apps to using gpu_ names.
Merge branch 'master' into test_gpu
Merge branch 'master' into test_gpu
Merge branch 'master' into test_gpu

Conflicts:
	test/correctness/hello_gpu.cpp
Merge branch 'master' into test_gpu
Merge branch 'master' into test_gpu

Conflicts:
	apps/bilateral_grid/bilateral_grid.cpp
	apps/interpolate/interpolate.cpp
	apps/local_laplacian/local_laplacian.cpp
Merge branch 'master' into test_gpu
Merge remote-tracking branch 'origin/master' into test_gpu

Conflicts:
	apps/bilateral_grid/bilateral_grid.cpp
	src/Func.h
	test/correctness/bounds.cpp
	test/correctness/bounds_inference.cpp
	test/correctness/chunk.cpp
	test/correctness/convolution.cpp
	test/correctness/debug_to_file.cpp
	test/correctness/gpu_large_alloc.cpp
	test/correctness/gpu_multi_kernel.cpp
	test/correctness/hello_gpu.cpp
	test/correctness/math.cpp
	test/correctness/param.cpp
Change gpu_tile to take Expr instead of ints. Leave cuda_tile taking
int for now as there no default constructor from all integer types to
Expr (e.g. size_t does not work) and so it might be a breaking
change. Moreover, cuda_tile should disappear.
Merge branch 'test_gpu'
Merge branch 'master' into test_gpu
NAming changes, add more uses of evaluate_may_gpu.
Merge pull request #244 from halide/master

test_gpu branch for better GPU test coverage, better naming.
Merge pull request #247 from halide/test_gpu

Test gpu