RoadMatcher: AdjustEndpoints button

Concerns:
* adjustment constraints
* line segment length check
* #adjustable returns String if there are Unknown incident segments
* undo?
* progress
* use original line if possible
* don't adjust twice! Get all candidates first then eliminate duplicates
* don't adjust both endpoints! One at a time. (Or iterate until 0 adjustments are performed)
* adjustment precedence rules

Q: How do we find the inconsistencies?
A: EndpointAdjuster#adjustable


Fire back some stats, like number of adjustments made, reasons for adjustments not being made

Constraints:
* max adjustment size/angle
* ...