Sync up java Tight decoder with recent changes to C client as much as possible. These changes should also fix the 16bpp issue reported in bug #3429667.  I think there are probably errors in the FilterGradient* code but I can't get any servers to actually send this type of data to test it.

git-svn-id: svn://svn.code.sf.net/p/tigervnc/code/trunk@4819 3789f03b-4d11-0410-bbf8-ca57d06f2519
8 files changed