Milky/selection border

[milkmanmatty]

Add 2 features:

Right-Click Places Last Selected Feature

While the actual placement functionality already exists in dispatcher.DragDropFeature(), the functionality around storing the last selected feature was not present. Also split the generic mouse-down event into mouse-left/mouse-right.

Functional Requirements:

• Right-Clicking after loading up Mappy initially, that is without any feature being selected, does nothing. This includes not crashing.
• Right-Clicking when the user has selected a feature places the selected feature at the mouse location.
• Changing the feature selection correctly changes the feature that is placed on Right-Click.

DoubleCombo Selection Border

To enable the user to easily see what item in the ListView is selected a thick red border was added. The actual appearance of the border matters little, the main thing is that the user can easily identify what is selected even when the ListView is not in focus.

Functional Requirements:

• Selecting a Section from the Section-List places a thick, red border around that Section.
• Selecting a Feature from the Feature-List places a thick, red border around that Feature.
• Selecting a Feature has no impact on a Section, or vice-versa.
• The thick red border is painted behind the image and/or the text of the item being selected.
• Changing selection within the list correctly removes the old selection border and repaints the border on the correct selected item.
• The red border stays visible when the list, or any part of the side panel, isn't in focus.