first pass at making an integer-only flavor of the libraries. move FLAC__real out...

first pass at making an integer-only flavor of the libraries.  move FLAC__real out of ordinals.h to src/libFLAC/include/private/float.h, add FLAC__double and FLAC__float and use these everywhere instead of double and float, and don't typedef FLAC__real/float/double when building in integer-only mode.  still need to provide integer substitutes in several places.