When dropping elements on "lines", help the users to connect them correctly

As a Modeller

I want to be able to drop an element on a line (either "line" or "relationship link") between two objects and get help with auto connecting to the elements between which I dropped the element.

So That modelling of certain diagrams (e.g. process flows) can be done more quickly and more "visio-like".

Benefits quicker modelling and behaviour more consistent with (surface level) comparable MS suite tools.

Acceptance Criteria 

1. Dropping an element on a "line" helps me (by some means) to connect the element correctly to the elements on either side of that line.

Customer / Originator LFV/non-architects

Priority medium