Removing restriction on plugin datatypes

Fix bug while adding new value to enumerated datatype list of values

Fix bug while using 'Close project' menu and a few POUs are opened

Fixing segmentation fault in debug

Fixing ToolTip behavior and bug with INOUT interface variables in Function Blocks and adding support for display connection point between wire and connector when mouse passing over.

Adding support for choosing graph range in duration instead of tick number when Common_Ticktime is available

Fix segmentation fault happening when changing POU tab selection

Adding support for loading datatypes defined in plugins to allow to use them in PLC program

Fix bug when trying to paste POU containing utf-8 characters

Fix bug with multiline tooltip on Windows

Fixing bug in displaying variable panel header on Windows

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