Merge branch 'Melanosuchus/patch_ui' into 'master'

Melanosuchus/patch ui

Various changes related to patch meshes.

* Global commands
  * Cleaned up some duplicate commands.
* Patch dialog
  * Added buttons to flip the texture
  * Added a button that select the proper axis for cap texture on the selected objects
* Cap selection
  * Now it generate caps with sensible texture coordinates (for axis-aligned patches)
* Surface dialog
  * Fixed patch texture buttons that didn't create undoable actions
  * Removed code duplication with the patch dialog

See merge request !2