#233 Hotkeys for next/previous error

[Patrick Kruse]

Currently, whenever you are using one of the error
panels (JUnit, Javadoc, Compiler errors, CVS diffs),
there are two little buttons on the right hand side to
go to the next and previous error, but there is no
hotkey to do this.

We have nearly every key bound to a hotkey. E is not.
It would be logical to view the next error, when an
error list pane is active, by pressing CTRL + E and the
previous error by pressing CTRL + SHIFT + E.