Visual Mode: fixed a problem where texture skewing didn't work correctly for textures scaled through sidedef properties. Fixes #985

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: changing brightness now affects sector brightness, holding Alt will change local brightness

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