Internal, build tools: use origin/master to get commits count and current hash instead of local master.

Updated the Eternity UDMF configurations with the latest items.

Added, Sector Edit window, UDMF: added UI support for "floor_reflect", "ceiling_reflect", "floorglowcolor", "floorglowheight", "ceilingglowcolor", "ceilingglowheight" and "fogdensity" UDMF properties.
Updated ZDoom ACC.

Internal: Git commit hashes are now shown in the Update window changelog.
Internal: Exception window now links to GitHub Issue Tracker instead of zdoom.org GZDB thread.

Internal: renamed several build batch files, updated relevant info in the documentation.

Internal: removed some old unused resource/test/documentation files. This reduces repository size by approx. 20Mb.