Merge pull request #85 from isuftin/master

Vertex, overwriting, baseline naming, UI tabbing
Merge pull request #86 from isuftin/master

Baseline overwrite
Added check for layer so it doesn't get clobbered.  For now just throw an exception if layer exists.
Merge pull request #87 from jiwalker-usgs/master

checking if layer exists first
Merge remote-tracking branch 'upstream/master' into workspace-per-session
Merge remote-tracking branch 'upstream/master'
Merge branch 'workspace-per-session'
Code cleanup
re-did code changes that may have gotten clobbered?
Merge branch 'workspace-per-session'