Copy and Paste Properties: fixed a problem where the "fadecolor" GZDoom UDMF sector property was not copied/pasted

MBF21 Game Configuration: Added missing "friendly" flag to things (thanks to hawkwind3). Resolves #703
MBF21 Game Configuration is now enabled by default

Fixed a problem where the display was desaturated in certain situations in classic modes when wireframe rendering was enabled when exiting Visual Mode. Fixes #619
Fixed a problem where sectors were not desaturated correctly in classic modes on map load

Visual Mode: fixed a problem where offsetting the middle texture of double sided lines would not work under certain circumstances. Fixes #702

* Extended rendering options for drawing vertices
* Fixed vertex scale slider behaviour
* Force plot highlighted vertex in DragSectorsMode
* Moved ShouldRenderVertices property into the properties region
* made config file variable lower case to be in line with other config file variables

Visual Mode: added actions to lower and raise map elements by the current grid size (no defaults bound). Resolves #699

Snap selection to grid: fixed a problem that could cause a crash if geometry got removed by snapping it to the grid

Visual Mode: fixed a problem that resulted in incorrect texture offsets when moving a texture by grid size, and the grid was a multiple of the texture size

OBJ Exporter: fixed a problem where the model path controls were disabled unless creation of MODELDEF was enabled. Fixes #692

GZDoom game configuration: added support for distinct upper/middle/lower sidedef brightness levels. Resolves #694

UDBScript: fixed a bug where changing a thing's or linedef's arguments did not recorded for the undo system

GZDoom game configuration: added enum list for the automapstyle UDMF linedef field

UDBScript: fixed a problem where getting a highlighted map element would not work correctly in some circumstances

Fixed a problem where polyobject numbers where not sorted correctly in the editing dialogs. Fixes #690

Visual Mode: added toggleable option to select all adjacent visual vertex slope handle when selecting a visual slope vertex handle. The action is called "Toggle Adjacent Visual Vertex Slope Selection"

UDBScript: the progress bar in the running script dialog now stops its animation when no progress was set and the script finished.

UDBScript: fixed a problem where the UDB.log() method crashed when a non-string object was passed to it

UDBScript: groups all classes, objects, and methods in a new UDB namespace, usable with the new feature version 4. Updated the documentation accordingly. Resolves #679

Added classic rendering mode to closer emulate software renderer visuals in visual mode

Added "Orbit" and "Move Camera to Cursor" visual mode actions (not bound by default)