Fix crash on attempt to save cached OpenGL nodes on OS X

Root permissions are required to be able to create directories inside /Library/Application Support
So user's ~/Library/Application Support is used to store cached nodes
- fixed: plane equation vectors must be normalized when being loaded from UDMF.
Fix crash when GL nodes file cannot be opened for writing

Report errors to console if nodes file cannot be opened or written
Remove redundant saving of GL nodes if they were loaded from cache
Don't reset the inventory of dead players
- fixed dynamic light definition for Hexen's blue candle.
Merge branch 'master' of https://github.com/rheit/zdoom
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.
Merge branch 'master' of https://github.com/rheit/zdoom
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' of https://github.com/coelckers/gzdoom

Conflicts:
	src/CMakeLists.txt