Added option to select behavior (Tools -> Preferences -> Editing) of scaling when auto-aligning textures on floors/ceilings (use base scale of 1 (default), use current scale as base, never scale)

Custom types for user defined UDMF fields could cause problems when fields with the same name used different types, so they are disabled for the time being (only bool, int, float and string are allowed now)

Update things before adding their geometry in visual mode so things don't go awry when realtime editing them. Fixes #393.

Aligning textures on the X axis now works correctly with negative scale values when world panning is not enabled.

There can be multiple different ambient sounds with the same sound name, so add the index to the name to differentiate them. Fixes #390.

Fixes for raisesectortonearest and lowersectortonearest action when used on slope handles to account for float rounding errors

Copy resource bitmaps before using them on a worker thread

Print a warning and skip parsing classes that try to inherit from themselves (instead of going into an infinite loop)

The sloping between handles action is now a bit more convenient and tries to figure out what the user wants to do even if not exactly two slope handles are selected.

- Smart pivot handles are now shown for the highlighted slope handle

- Added action to slope selected floors/ceilings between selected slope handles (default key: Ctrl-F)
- Added Shift-W as default key to toggle visual slope picking

- If geometry is selected and the geometry the modified slope handle belongs to is not selected it will now also be modified
- Made the slope handles hover closer to the geometry

Improved drawing length of slope handles on sloped lines (still too short, possibly because of aspect ratio correction?)

The slope handle closes to the mouse cursor will now always be picked (no minimum distance required anymore)