Guides with itself as source

[lukasvdelft]

Really nice this work! I have a feature request. I am working in architecture and sometimes walls or other objects need to be extended, so for instance in the case of a wall, polygon is a rectangle, one of the short lines needs to be moved. So both vertices need to be moved in line with the long lines. If the "guides" would also work on a single object this would be very helpful. Much more complicated would be selecting an edge (two vertices) and move the two at the same time in line with a guide.

Btw do you foresee publishing a d.ts typings file in the future?