#2801:subtensor-incsubtensor

Import numpy

[REG, CRASH] fix crash related to float16 introduced in gh-5077

warn when profiling.ignore_first_call isn't used.

Make test for cast to/from int/float16 and make sure to have a cast in the inner graph instead of identify. (it was still working with identity, but having an explicit cast is better)

Fix cache

Fix crash introduced by gh-5077 by keeping GpuElemwise as original and only casting to float16 in the code generator.