Add Lagarith support (fourcc: LAGS)

As requested in: http://forum.videolan.org/viewtopic.php?f=14&t=61099

Currently VLC can't open video data that is compressed using Lagarith codec. AFAIK libavcodec doesn't support it yet, so manual labor is required.

Sample file (fourcc LAGS): http://samples.mplayerhq.hu/V-codecs/lagarith/lagarith.avi

Source code http://lags.leetcode.net/codec.html