Corrected all rate calculations for TERMALL mode - now we don't need to increment pass rates for TERMALL.

correction should be zero for TERMALL, since all necessary bits are output from registers during flush

If we don't do this, then setting from previous file will affect next file.

2. add one to pass rate at end of block encode (except for TERMALL), to ensure that it matches actual number of encoded bytes
3. use correct lazy length computation for pass rate correction factor (p 498 from T+M)

store to PNG: force libpng to allow Microsoft/HP 3144-byte sRGB profile, normally skipped by library