Add action for path edit
I am working on a plugin that helps with making tessellating patterns.
some thing like this: 
![tesselation](https://user-images.githubusercontent.com/5008461/51009276-67f9fe00-1504-11e9-9879-c1dce6a7fa48.gif)

However instead of using 2 symbols it would use a single shape. Ideally I would like this plugin to work the same way as the transform tool.

Right now I am using the `SelectionChanged` event however that means to get the shape to update I need to toggle in and out of the path editing mode.

**Action to add:**  Focus/blur events on path points