[variables] Allow deleting variables with delete key and context menu

[Former user]

Originally reported on Google Code with ID 428

When the variables view is open, pressing the Del key and right click do not do anything.

It would be nice if it were possible to delete a variable from the variables view either
by pressing a some keys or through a context menu.

I am currently using SpeedCrunch 0.10.1 on Ubuntu 12.10.

This is a feature request with admittedly low priority. I think speed crunch is overall
a wonderful and incredibly useful piece of software for daily use. If this feature
does not take a lot of work, it would be nice to see.

Reported by jfoxrabinovitz on 2013-02-08 13:25:57

[Former user]

https://github.com/speedcrunch/SpeedCrunch/commit/b4164583d4833d093531c67267c825b6ee38ae07

Reported by helder.pereira.correia on 2013-02-11 09:20:02 - Status changed: Fixed - Labels added: Type-Enhancement, Priority-Low, OpSys-All, Milestone-0.11, Component-UI, Usability

[Former user]

That was really fast. Thank you!

Reported by jfoxrabinovitz on 2013-02-11 12:59:35