A few improvements to the UI:

• Changed merging to add a "confirm merge button"
• Fixed the select whole route in annotation so that it works properly with branching and looping paths
• Fixed z-selection so that the robot is always on top
• Changed waypoint markers so that only those with modified names are persistently shown
• Fixed the error selection so the default name can be typed as a target.

Known remaining items:

• With branching paths, extra lines are created that look cluttered
• Need to add instructions for the 3 point selection (The 3 point merge selector is confusing to use #45 )

close #234