Allow for saving screenshots in PNG format.
Allow for PNG screenshots.
Add some strictly unnecessary curly braces.
Remove 0 summand.
Add PNG screenshots to advanced video options menu.
Merge pull request #361 from fabiangreffrath/png_screenshots

Allow for PNG screenshots.
Merge https://github.com/chocolate-doom/chocolate-doom into crispy-doom
Merge https://github.com/chocolate-doom/chocolate-doom

Conflicts:
	src/v_video.c
Merge branch 'master' into crispy-doom

Conflicts:
	src/m_config.c