Adding shortcut key for MeasureIt for Firefox.

/*depreciated*/
This no longer works with newer versions of firefox since the Keyconfig extension is dead. I use Greenshot for imagegrabbing, and that displays the pixel size.

Start by grabbing
Keyconfig.

Go to Tools->Keyconfig->Add a new key->Code is
"net.kevinfreitas.measureit.toggle();"

The shortcut key won't work to turn of MeasureIt, but you can use ESC for that.

I use CTRL-E, good for left hand when right is on the mouse, and not really used for anything (it's bound to web search, but you can unbind it easily)