[sch/brd] push and shove for a single trace

[abetusk]

You should be able to select a single wire/trace and push and shove it around instead of deleting then relaying down.

priority: high
estimate: 4

[abetusk]

This doesn't need to be overly complicated at first. Select edge and move it in the two simple directions it's allowed to move by the neighboring trace constraints. Select a vertex and alter the two traces it connects. Don't allow for net connection.