Added: thing categories defined in Game Configurations can now be nested.
Changed, Thing Edit window: thing categories now use different icons.
Fixed: Thing Edit and Vertex edit windows had incorrect help links.
Fixed: Sound Propagation and Sound Environment modes had incorrect help links.
Documentation: updated "DECORATE keys" and "Things Settings" pages.
Game Configurations: updated things in ZDoom "Bridges" category to use argument types 23 and 24.
Documentation: added "Action Argument Settings" page, updated "Basic Settings", "Map Format Settings", "Linedefs Settings" and "Things Settings" pages in Configurations -> Game Configurations group.
Documentation: updated "DECORATE keys" page.
Removed "Sectors Brightness Mode" action, because the mode itself was removed long ago...
Documentation: updated "DECORATE keys", "Things Settings" and "Linedefs Settings" pages.
Added, Game configurations: added "thingclasshelp" property. It's used to open a website when thing class name is clicked in the Thing Edit form.
Changed, "Raise/Lower sector to nearest" action: 3d floors are now taken into account when using the action on things.
Updated documentation.