SoftQuake 1.1.0

1.1.0 binary release of SoftQuake

• Add PNG support for screenshots. Set ENABLE_PNG = 1 in 4_options.mk or meson.build to enable.
• Fix file handle leak in cd_sdl.c.
• Add host_maxfps cvar. Defaults to 72 as in the original game. Set to lower values to emulate lower framerates.
  Values above 72 may cause physics bugs.
• Increase cd audio buffer size from 512 to 1024 bytes.
• cd audio is no longer audible if the cvar bgmvolume is 0 when the game is launched.
• Provide a better error message when using sw_backend.
  Specifying an invalid video backend with sw_backend will now notify the player immediately, instead of on the next restart.
  SDL2 will be used as a fallback, as before, except that now it will set the cvar to "sdl". Previously it did not.
  sw_backend only affects the software renderer. GLQuake remains unaffected, but can still access this variable.
• Add precompiled header to Makefile build. This speeds up the Windows build by almost 2x.
  If you're compiling the game yourself, you may want to delete the header manually after building,
  since it can take up quite a bit of disk space. In this build, the file is quakedef.h.gch
  Otherwise, the file is removed as part of the clean target.
• Fix clean target for Makefile. Now all targets are cleaned properly.
• Implement D_BeginDirectRect in the software renderer.
  This draws the loading icon in the top-right corner, just like in the DOS version.