_afterPaletteDrop now returns result as expected
Adds comment to connectToAllLayers
Adds comment for how _onBack needs improvement
Adds setInvalid to autoCompletion
Strips out stuff seen as html tags from Compiler output
Reformat code
Fixes drag multiselect and drag & drop in model/services tab
Issues: WM-4873

1. Shift click in model now selects all widgets between closets
selected widget/component and the component being selected.

2. Dragging components within the model tab now fires an
onNodeDrop event for EACH of the selected components, not just
the currently selected component.