Implemented imm_atomic_iadd
Implemented atomic bitwise and.

Updated tests\ps5\atomic_mem to use more atomic instructions.
TranslateAtomicMemOp now handles all atomic memory operations.
ITOF/UTOF fix for float sources

When the source to ITOF/UTOF was thought to be float, the code
previously gave a warning and ignored the instruction. No longer ignore
the instruction under these circumstances since although there is no
conversion to be done, the src and dest operands might be different
registers.
Support writing imm_atomic return values to int/uint temps.

imm_atomic operations return the previous value of the UAV/thread group
shared mem. Previously the variable to hold this result would have a
floating point type, now it can be int/uint if appropriate.