* new icon with two "sciscors" indicates that there will be more than one split perfomed
* the tooltip mentions that one can limit to a single line
closes#8818
Make context the first argument of operation objects
Add Paste operation to edit menu when opening the context menu on a blank area of the map (close#2508)
This commit includes a bunch of minor things:
- change keyboard shortcut to 'E' to not conflict with anything
- move `disabled` check from operation into action and simplify
- use `actionMoveNode` to place the detached node at the mouse cursor
- disable the operation if the node is connected to hidden features
- lots of code simplification
- make the icon more centered