[DF-748] Remove UNDOManager from project for MacOS. Remove UNDOManager files.
[DF-749] ExecuteAndRelease() method added to the CommandsManager. Executing and releasing of the commands were replaced with calling of this method.
[DF-754] IsAcceptNode method renamed to IsNodeAccepted
[DF-755] [DF-756] Fix not obvious code
[DF-751] Fix GetArrowsNode function
[DF-748] Fix Win32 project
Merge remote-tracking branch 'origin/DF-31_Undo_Redo_2' into DF-31_Undo_Redo_2
[DF-760] Fix memory leak in heightmap editor commands.
[DF-759] Fix CommandInternalRemoveSceneNode::GetNodeIndex() method for more obvious return value
[DF-754] Fixed merge conflict