spearmint: Don't check world surfaces in RE_GetViewFog

It won't work correct and caused RE_GetViewFog to show up fairly high on performence report.
spearmint: Don't sort unused surface sort bytes

Disable some unused sort bytes for better performence.
spearmint: Make DMA active loop sounds a linked list

Increasing the number of entities makes AddLoopSounds and ClearLoopingSounds
slower (~2% execution time vs ioq3 ~0.5%), so use a double linked list of active sounds
(~0.05% execution time).
spearmint: Remove two unused ET bmodel variables

bmodel visible usage was commented out in ET's RB_CalcFogTexCoords.
I didn't see a usage of bmodel entityNum.

Also, bmodel visible was suppose to be cleared in RE_ClearScene.
spearmint: Fix infinite loop caused by active loop sounds link list

Let's not always set next's prev to NULL.

Caused freeze at start of Team Arena's mpq3ctf2 map.
spearmint: Check number of bsp surface vertexes on load

Error on load if bsp surface has too many vertexes instead of when it's drawn.
This is already done for models.
spearmint: Clear viewangles on level change

cl is cleared before parsing gamestate. Move viewangles back to cl like in ioq3.

This also fixes a issue in debug builds where sometimes I'm unable to turn the view
after idlogo cinematic plays. Zero frame msec causes divide by zero in CL_KeyState
resulting in viewangles being NaNs and not able to be changed using -= or +=.
spearmint: Improve handling of missing default.cfg

When connecting to a server if default.cfg is missing I made
Spearmint fallback to last valid game and proceed to download mode
which causes a filesystem restart and everythings good. Well, that is,
if the client actually downloaded a pk3 with default.cfg in it.

This commit fixes handling cases where downloads are disabled or
default.cfg is not in the missing pk3s. By fix I mean it gives a sane
error now. This is easy to cause by running a dedicated pure Team Arena
server without putting the required mint-game.settings in a pk3 and
connecting using a client.

Also fixed trying to download files that exist but are not in search path,
which happens in fs_game fallback download mode.
spearmint: Always restart filesystem at connect

If a pk3 is downloaded or fs_game is changed the file system is restarted.
Though if that is not the case, the file system still needs to be restarted
at least once to reload mint-game.settings.

This causes Team Arena single player with sv_pure 1 to require mint-game.settings
to be in a pk3. This is the intended behavior.
Merge branch 'master' into sdl2