Batch instruction highlighting with multi-select

[D0ntPanic]

Now that selection of multiple lines is supported across all views, it should be possible to select multiple instructions and highlight them all with a color from the UI easily. Right now, selecting multiple instructions and highlighting only highlights the last instruction.

[agnosticlines]

Hey, just registering interest in this, the highlighting feature is really powerful, and while this could be done with a plugin the colour previews are really nice in the menu

[xusheng6]

To clarify, this issue means multi-selection of continuous instructions, which is already do-able currently