#21 Add defines for a "release build"

[Bit Weasil]

It would be nice to do certain actions on a release - bind the .cl kernels into the binary based on the defines, and perhaps turn on some optimizations. Please add such an option.

Also, please add an option for global optimization. Not having -O3 throughout aids debugging, but was killing CPU kernel performance. I added it to that specific build, but it would be nice to normally build with -O3 unless a debug build was being used.