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