Slight macro improvement -- makes robust to certain substitutions involving *R
FreeBSD: Ensure only one of USE_GCC_ATOMICS or USE_TBB is defined
Includes addition of -march=i586 when building for i386 target
this ensures that instructions for gcc atomics are available to compiler
Adding a swap command line option for swapping the top two
layers of the stack.
Document oiiotool --swap, also check error condition.
oiiotool --fill : bug fix, was zeroing out image instead of filling on top.
Also alter --create to specifically make a float image internally, since
so many operators take only float. Add test that fill works.