set translation start / stop, and set longest orf ...

... only work on a single transcript. Rename methods to reflect that. Allow
these menu items only when transcript is selected.

Signed-off-by: Anurag Priyam <anurag08priyam@gmail.com>
Recalculate orf when transcript is dragged to edit track and on each edit.

Signed-off-by: Anurag Priyam <anurag08priyam@gmail.com>
Fix a bug which could cause an edit action to not be reflected.

Signed-off-by: Anurag Priyam <anurag08priyam@gmail.com>