VegBank

People should be able to mark 2 extant plots as duplicates, but should also be
able to download plots into VegBranch (this exists), then add new observations
to VegBank Module of VegBranch, and declare the new observations "upated
versions" of the same plots. Then VegBank needs to digest all this.

VegBank also needs to treat observations which have newer versions differently.
By default they should be hidden from the main queries, though when looking at a
plot that has an older version, you should know that it has an older version and
be able to click to get to it.

PLOT in this bug means observation, really.

Original Bugzilla ID was 971