check HTTP response codes when querying using HEAD... if an error occurred, detect it ASAP
(and check Last-Modified using HEAD just like we check Content-Length)

git-svn-id: svn://svn.icculus.org/fs2open/trunk@11030 387891d4-d844-0410-90c0-e4c51a9137d3
additional error checking

git-svn-id: svn://svn.icculus.org/fs2open/trunk@11031 387891d4-d844-0410-90c0-e4c51a9137d3
ngld's fix to spoof the user agent to bypass 403 Forbidden errors

git-svn-id: svn://svn.icculus.org/fs2open/trunk@11032 387891d4-d844-0410-90c0-e4c51a9137d3
bump version

git-svn-id: svn://svn.icculus.org/fs2open/trunk@11033 387891d4-d844-0410-90c0-e4c51a9137d3