Either allow disabling vertex auto-snap, or put an extra undo step

[ioan-chera]

I got such a request from a user and I'm sure that most people would prefer that to be available. It's a common editor design that complex operations can be undone partially in order to achieve the less likely, but still valid, intermediary outcome.

In this case it's how vertices are automatically snapped to the nearest line to cause splitting. Sometimes you do not want this splitting to occur, because you want linedefs to be overlapped. Right now Undo reverts the whole operation.

[UlisesMeteorbyte]

(I am RataUnderground in Doomworld)
Although this also seems like a desirable feature to me, to be clear, with my request to disable auto snap I meant that it is difficult to draw accurately at times because when you try to draw vertices very close to another line, it comes together and does merge. If I want to make a sector one or two units wide, I have to use the numerical parameters in the properties panel to move the vertices exactly where they correspond, instead of moving them with the mouse as is the usual workflow.