#31 Allow keyboard shortcut customisation

[Tiny Clanger]

The keyboard shortcuts are fixed. This is a problem as Refresh is bound to F5 rather than the more standard* Ctrl-R, meaning that I keep thinking there are no changes to the repo when in fact there are.

Please could we have a means of changing the keyboard shortcuts from within the program? Making a custom build and repeating the process every time there's an update is a bit of a sledgehammer approach to this…

Thanks

*: F5 might be standard for Internet Explorer users, but non-Windows users are more used to Ctrl-R. I'd be happy with both shortcuts working for Refresh if keyboard shortcut customisation is too tricky to implement :)