Let's go float!

Changes:
1. Move uint16 -> float conversion from always-on temperature iop to new always-on letsgofloat iop, which is supposed to be first-one in the pipe.
2. Fix issues created by this move.
3. Implement OpenCL kernel for letsgofloat iop.
4. Fix issues created by this move.
5. Implement OpenCL kernel for Invert iop.