Disappearing servers fix

See merge request STJr/SRB2!334

Fix servers disappearing from the server list when you refresh, by forcefully closing connnections to the servers immediately after sending ASKINFO. Also force close connections to old server list when refreshing, because we don't need to hear from them anymore full stop.

FOF wall rendering fixes and cleanup

See merge request STJr/SRB2!317

Fix the nonsense going on here regarding dc_colormap, this makes FOF walls appear strange if they were for a fog block with colormap adjacent to a normal sector with a colormap and no FOFs.

...that was a mouthful

MinGW: Fix compiling on 64-bit Windows.

See merge request STJr/SRB2!329

Should fix libgme depending on two DLLs externally.

Camera subsector crash fix

See merge request STJr/SRB2!318

OpenGL HUD scaling fix

See merge request STJr/SRB2!320

Fix stringop-truncation: ‘strncpy’ output truncated before terminating nul copying 8 bytes from a string of the same length

Fix =sizeof-pointer-memaccess: argument to ‘sizeof’ in ‘strncpy’ call is the same expression as the source; did you mean to use the size of the destination?

Fix desynch when toggling analog mode or flipcam

Update SDL Mixer to 2.0.4

See merge request STJr/SRB2!322

Update SDL2 to 2.0.9

See merge request STJr/SRB2!321

Remove unnecessary SDLCALL from IMG_xpm.c declarations

See merge request STJr/SRB2!327

Missed #ifdef HAVE_LIBGME in win_snd

See merge request STJr/SRB2!326

mixer_sound fix x64 build issue

See merge request STJr/SRB2!323

Save the current renderer to screenshots.

See merge request STJr/SRB2!324