Fix bug in xmlclass when allowing custom class attributes definition on inherited classes

Adding support for defining a description for a user POU type, and displaying this information in library tree.
Adding support for displaying a tooltip containing the informations of a function block when passing mouse over it in a graphic editor.

Fix bug in refreshing menu after tab selection changed

Adding support for checking location validity when filled by user

Fixing bug when building textual code containing comment with special characters

Fixing bug on Windows with refresh when moving Viewer with scrollbars

Adding support for using shift key with rubberband for adding a group of elements to the current selection

Fixing bug in autoindent when number of spaces at the beginning of line is odd

Adding support for Drag'n dropping panels between notebooks

Fixing bug in highlighting in variable panel

Adding support for drag'n dropping variable from global defined in configurations and resources to POU variable panel or body editor for declaring external variables
Adding support for drag'n dropping located variables from topology panel to configurations and resources variable panel for declaring global located variables

Adding support for using ESC key for closing custom grid cell editors

Disabling drag for modifying grid row size

Fixing bug conflict on tab selection between POU editor and Debug window of an instance of this same POU on Windows

Fixing bug in Debug with ToolTip for wire value disappearing on Windows