MINGW/MINGW64 implies SDL.

Cmake: fullscreen fix

See merge request STJr/SRB2!1226

Fix compiling using cmake if internal libs is used

See merge request STJr/SRB2!1225

Use SSE3 in 32-bit x86 binaries

See merge request STJr/SRB2!1213

All because of a typo

Add multithreading option for CMake

See merge request STJr/SRB2!1204

Fix gzip failing to compress SRB2's objdump on non-Windows.

See merge request STJr/SRB2!1191

2.2.8 prep

See merge request STJr/SRB2!1170

Fix uninitialized variable issue in patches with missing grAb chunks

See merge request STJr/SRB2!1171

Prevent Canarivore gas from teleporting up walls

See merge request STJr/SRB2!1154

Fix #178

Closes #178

See merge request STJr/SRB2!1112

Remove "The OpenGL renderer is incomplete" notice (closes #281)

Closes #281

See merge request STJr/SRB2!1169

Fix graphics replacements not taking effect via -file

See merge request STJr/SRB2!1168

This reverts commit 569453ee.

And one line from b6089ccd.

This is needed for graphics replacements to take effect.

Fix net ids broken AGAIN (closes #310)

Closes #310

See merge request STJr/SRB2!1166

This is so netvars registered by any lua scripts will load in the correct order.

Credits changes

See merge request STJr/SRB2!1161

Replaced some of the lower resolution variants with some smoother downscales. The 16x16 one is even Sonic's 1-up icon from the game!