Cut bug fixing:

* Disable "Add/Edit connectors" button then cut to parts
* Fixed flip_cut_plane()
* Fixed cut by Line, when draw line over the cut plane
* Fixed apply of the transformations, when cut to parts

Cut improvements:
* Process "Ctrl"
* Change color of the cut plane when it's hovered
* Don't apply Cut information for result object(s), if cut doesn't have any connector or is cut to parts
  (partially related to #9633 - Add option to Invalidate Cut Info at the time of cutting)

src/libslic3r/Model.hpp

@@ -316,7 +316,7 @@ enum class ModelVolumeType : int {
     SUPPORT_ENFORCER,
 };
 
-enum class ModelObjectCutAttribute : int { KeepUpper, KeepLower, KeepAsParts, FlipUpper, FlipLower, PlaceOnCutUpper, PlaceOnCutLower, CreateDowels };
+enum class ModelObjectCutAttribute : int { KeepUpper, KeepLower, KeepAsParts, FlipUpper, FlipLower, PlaceOnCutUpper, PlaceOnCutLower, CreateDowels, InvalidateCutInfo };
 using ModelObjectCutAttributes = enum_bitmask<ModelObjectCutAttribute>;
 ENABLE_ENUM_BITMASK_OPERATORS(ModelObjectCutAttribute);