Added assertions to halide_release, some small style tweaks
Added debug output of generated PTX code (in place of doing it in the runtime)
Improved error handling to be on even without DEBUG
Added timing around malloc, copy_to_host, copy_to_dev, and dev_run
Added timing around dev_sync, dev_free, init_kernels
Merge branch 'cuda_error_handling'
Merge branch 'gpu_timing'
Fixed asserts in halide_release to accept CUDA_ERROR_DEINITIALIZED.
Merge pull request #314 from dsharletg/master

Improve error handling in CUDA target