Fixed, Sound Environment mode: fixed several cases when single-sided lines with only back side could cause either logic errors or crashes.
Fixed, Automap mode: fixed several cases when single-sided lines with only back side could cause logic errors.
Debug: added some debug code to WAD.Insert() to investigate the issue when lumpoffset could become negative.
Changed, Map Analysis mode: the view is now much more zoomed after clocking on a "Check very short linedefs" error check result.
Removed single testing engine launchable by the editor at once limitation (it worked properly only when using Test map actions anyway).
Fixed: re-did the fix for invalid geometry created when drawing very large grids from R2653, because it caused other issues.
