win32 binaries that include sound (gstreamer) complain about missing python2.6

[Antoine Martin]

Apparently, we ship libgst-python2.6.dll and some duplicate copies of the DLLs (that's because some get bundled by py2exe and others are copied by the BAT file..)

So:

• remove anything python2.6 related from the output - should fix the alert dialog
• remove the duplicates
• trim down the number gstreamer DLLs that we ship (remove all the rtp, video, ...) - should reduce the size of the installer (somewhat related to #253 and #103)

All this, as cleanly as possible... using (educated) trial and error might still be the fastest approach.

[Antoine Martin]

r2748 removes the python2.6 warning

[Antoine Martin]

r2776 removes the GStreamer plugins we don't need when building with sound - reduces the compressed installer output size by about 2MB (actual disk space used by much more - and more importantly, far less clutter)