Clean up 32/64 macros
Add LUT generation framework; LUT for 1/x
Rework fix_exp to use external LUT, proper 64/32 macros
Fix underflow bug in FIX_MUL_64
fix_exp: Compute iteration counts based on FIX_FRAC_BITS, add comments
Compute number of squarings possible in fix_exp
Improve test.c macros
Add a CHECK_DIFFERENCE test macro and update exp tests
Handle large negative numbers in fix_exp
Change overflow notification in FIX_MULs to OR with previous value