spearmint: Fix --version crashing

FS_GetCurrentGameDir trys to dereference fs_gamedirvar which hasn't been initialized.
spearmint: Merge PAKSUMS and gameconfig.txt to mint-GAMEDIR.settings

The new filename for mint game settings is mint-GAMEDIR.settings.
It is loaded from pk3 files, whereas PAKSUMS was not because I don't
know how to get file from a specific game directory.

Currently, only paksums are added from basegame settings files.

I originally wanted to put the extra settings in PAKSUMS, but instead I
added gameconfig.txt because it didn't fit the filename.

I removed support for PAKSUMS' "config noPakMismatchWarningDialog".
spearmint: Update references to gameconfig.txt
spearmint: Fix downloading standalone games from server
Fix FS_FOpenFileReadDir non-zero file handle when file not found in pk3

If a pk3 search path is passed to FS_FOpenFileReadDir, a non-zero
file handle is returned if file is not found. This causes incorrect
behavior in FS_ReadFileDir (when a pk3 search path is passed in)
which only checks file handle, not length, for seeing if file exists.

I don't know of any issues in ioq3 caused by this.
Merge remote-tracking branch 'ioquake3/master'
spearmint: Let's not put fs_game in mint-*.settings filename

Always use the same name, mint-game.settings. (Unrelated to mint-game VM...)
Added new function to load from specific game directory.
spearmint: Fix loading mint-game.settings from .pk3dir directories
spearmint: Allow game to specify SURF_NODRAW for renderer

It's the only contents/surface flag the renderer actually needs to know,
others it sets from surfaceParm keywords itself and later compares.

Also the value of SURF_NODRAW was changed in SoF2/JK2/JA.
Merge branch 'master' into sdl2