Update source copyrights to 2018

See merge request STJr/SRB2!346

Extra credits update .21

See merge request STJr/SRB2!345

Fix M_FindResponseFile returning garbage data

See merge request STJr/SRB2!254

Render the skies correctly on splitscreen in OpenGL mode

Render the startup screen on OpenGL mode

m_fixed: asm: cc is not a register

Add myargmalloc boolean to detect whether we allocated myargv ourselves or not, so we don't free myargv if we didn't

2.1.21 credits update

See merge request STJr/SRB2!339

Add README and LICENSE for installs

See merge request STJr/SRB2!335

Make the credits pics darker

See merge request STJr/SRB2!336

Make the error less confusing

See merge request STJr/SRB2!337

Master Server Update alert fix

See merge request STJr/SRB2!333

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

Make sure GetMODVersion and its console equiv properly detect failing to get a reply from the MS, also added extra console/menu messages

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