Add dwa test images to dist (tarball) manifest.
Also drop README.win32 from tarball.  (Already removed from repo.)

[New Cmake-centric instructions covering builds for Windows and other
platforms to follow.]
Merge pull request #127 from openexr/tarball_contents_fix

Tarball contents fix
Fixing SSE2 byte interleaving path to work with short runs
Merge pull request #137 from karlrasche/interleaveByte2_sse_bug

Fixing SSE2 byte interleaving path to work with short runs
Merge remote branch 'upstream/develop'