Added a check that doesn't print empty obituary strings, as wad's that hide obituary strings in multiplayer games end up spamming a lot of empty lines.
Prediction was rebuilding too much thinglist data

- Stopped player prediction from rebuilding more sector list data then
the player originally had.
definition for model vertex buffer.
Merge branch 'master' of https://github.com/rheit/zdoom
Merge branch 'master' into Glew_Version_For_Real
Multi-intermission waits for all players + changes

- Added a segment of code that now makes the intermission wait for all
players before advancing, instead of continuing on any player. A "ready
icon" shows to reflect this.

- The Deathmatch intermisson couldn't show the ready icon (because it
just used the ingame scoreboard), so a proper intermission was added,
which reflects the same design as the coop scoreboard.

- The colour column wasted more space then it should have needed, so it
was replaced with player colour backgrounds.

- Slight y offset adjustments to make everything fit in 320x200
properly.
Added wi_autoadvance

- Prevents an absent player from stopping the intermission
fix detection of libglew library on GNU/Linux
Merge branch 'master' of https://github.com/rheit/zdoom
Merge branch 'master' of https://github.com/darealshinji/gzdoom
Merge branch 'master' into Glew_Version_For_Real
- simplified MD2 drawing code as preparation for a buffer based implementation.
- cleaned up MD3 rendering and merged RenderFrame and RenderFrameInterpolated into one function.
- removed the voxel vertex buffer because it needs to be gone before implementing a model vertex buffer.
- initialize model data at engine start, not at level start.
- create vertex buffer data for MD2/DMD models.
- more vertex buffer stuff for models, still not tested.
- changed alpha texture handling to avoid using the deprecated GL_ALPHA8 texture format unless we have a compatibility context of an older GL version.
removed all GL 2.x code.

After thinking about it for a day or so I believe it's the best option to remove all compatibility code because it's a major obstacle for a transition to a core profile.
- some cleanup after GL 2.x code removal
- reinstated burn warp with shader based code.