end/start point arrows (#247)

Redirecting a arrow gives me cramp in my arm/hand. That is caused by the to small start, end and breakpoints of the arrows/lines.

Ingredients are:

- the 'click' area is very small.

- the resize box around the arrow has large click areas for stretching etc. and hinders grabing the end/start points additionally in case of a diagonal arrow.

I would like to have easier (bigger) handles for start, end and linebreak points.

Brainstorm:

Why do you need a resize box arround an arrow? The begin, end and possibly existing line break points can be draged by themselfs. The label could be dragged on its own.

If you remove the 'resize box', you could add those bigger handles.