and improved some comments). Also, made the documented {f,s}uword() functions the standard entry points and the undocumented {f,s}uword64() functions alternative entry points, like {f,s}uword32() for i386's. The bitrot in the comments was a little larger here -- there are new undocumented 32-bit sub-word functions, not just renaming of 16-bit functions from documented ones to undocumented ones.