Keyboard Shortcut for Updating from POT file

[ravage84]

Context:
We are working with managable-sized translation files for our web application projects based on CakePHP.
The POT files are generated through semi-automated means.
Afterwards, the PO files of the usually 1-4 languages/locales will get updated manually by using "Update from POT file..." in Poedit.

Feature proposal:
It would be nice to have a keyboard shortcut for the "Update from POT file..." functionality.

Rationale:
Since updating from a POT file is (very likely) a very common occurring step in the translatio processes of many,, it improve the UX of many without adding a lot of complexity to the application.

Alternative/Addition:
Alternatively or in addition to the keyboard shortcut for this function, a button in the main tool bar could be added for it, just like for "Update from source code".

[vslavik]

Happy to accept your PR.