Visual Mode: added support for GZDoom style texture skewing

Visual Mode: the effect of slope things are now only applied if they are specified in the game configuration

Game Configurations: added support for enabling or disabling support for vertex heights in UDMF game configurations

Visual Mode: fixed a problem where flood selection did not work correctly when sidedefs were previously marked by other actions

Visual Mode: fixed a problem where flood selection would operate from all selected surfaces and not just the clicked on one. This behavior can be reverted by enabling the "Use buggy flood select in Visual Mode" option in Preferences -> Editing (#969)

Visual Mode: fixed a problem where flood selection would operate from all selected surfaces and not just the clicked on one. This behavior can be reverted by enabling the "Use buggy flood select in Visual Mode" option in Preferences -> Editing

Visual Mode: fixed a problem where floors/ceilings could not be changed in size if the user tried to change their texture offset in a non-UDMF map

Visual Mode: fixed a problem where sloped 3D floors with an alpha value of less than 128 were not shown at all instead of fully opaque. Fixes #954

Visual Mode: when applying camera rotation and pitch to things a status message will now be displayed. Fixes #955

Visual Mode: fixed an issue where trying to apply a rotation to things that were not seen yet would cause a crash

Visual Mode: fixed a problem where the selection order was not kept when synchronized selection between visual and classic modes was enabled. Fixes #938

Visual Mode: fixed a problem where things directly touching the top of 3D floors were rendered with the incorrect brightness. Fixes #940

Visual Mode: changes to Eternity Engine's upper/lower texture skewing definitions are now shown in Visual Mode

Visual Mode: fixed a crash when toggling visual vertex slope picking and the map contains double-sided linedefs without a front sidedef. Fixes #928

- fixed a rare condition where skewed mid textures were not clipped correctly
- fixed a problem where translucent mid textures were not skewed correctly
- fixed a problem where sprites were skewed unintentionally

Disabled visual sloping for game configurations that do not support plane equation slopes. Fixes #828
Added toasts for visual sloping events

Behavior can be configured in the "Toasts" tab in the preferences.

Visual Mode: fixed an issue where using the "apply camera rotation to things" action did not update the thing cages properly

Visual Mode: Fixed a problem where using visual sloping a slope handle around itself resulted in invalid slopes

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

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

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

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

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"

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)

UDBScript: Exported the classes Linedef, Sector, Sidedef, Thing, and Vertex, so that they can be used with instanceof
UDBScript: Map class: the getSidedefsFromSelectedLinedefs() method now correctly only returns the Sidedefs of selected Linedefs in visual mode (and not also the highlighted one)
UDBScript: Map class: added a new getSidedefsFromSelectedOrHighlightedLinedefs() method as the equivalent to the other getSelectedOrHighlighted*() methods
UDBScript: Sector class: added new floorSelected, ceilingSelected, floorHighlighted, and ceilingHighlighted properties. Those are mostly useful in visual mode, since they always return true when the Sector is selected or highlighted in the classic modes. The properties are read-only
UDBScript: Sidedef class: added new upperSelected, middleSelected, lowerSelected, upperHighlighted, middleHighlighted, and lowerHighlighted properties. Those are mostly useful in visual mode, since they always return true when the parent Linedef is selected or highlighted in the classic modes. The properties are read-only
UDBScript: added new example to apply textures for floor/ceiling and upper/middle/lower texture for selected map elements
UDBScript: updated documentation

Added map scripting capabilities to UDB (#656). Documentation at https://biwa.github.io/udbscript-docs/

Visual Mode: fixed a bug where textures on 3D floors were not scaled correctly when using the upper/lower texture 3D floor flags. Fixes #640

Eternity Engine game configuration: it's again possible to set the floor and ceiling brightness independently from the sector brightness