Merge branch 'master' of https://github.com/halide/Halide
Merge branch 'master' of https://github.com/halide/Halide
Merge branch 'master' of https://github.com/halide/Halide
Merge branch 'master' of https://github.com/halide/Halide
Merge branch 'master' of https://github.com/halide/Halide
Merge branch 'master' of https://github.com/halide/Halide
Merge branch 'master' of https://github.com/halide/Halide
Fixed multiple contexts being created/shared incorrectly.
Removed DEBUG_PRINTF macro
Fixed attempt to reuse freed OpenCL platform
Merge pull request #197 from dsharlet-intel/master

Using a single global context for OpenCL