Fixes a problem running in Mavericks.

For some reason this worked before and now it doesn't.
The xib specifies NSMutableDictionary as the class for the array
controller but the cell can't be edited.
Making a mutable copy of the internal objects fixes it.
Perhaps only fails when the advanced colors prefs were created on a
different OS X, my case.
Clear logs with ESC key or toolbar button.

Much-needed addition. When you're debugging holding the iPhone in your
left hand it's annoying typing a left-hand shortcut (shift-command-R)
with the right hand or drop the phone. Reaching the mouse to use the
menu is not even under consideration.
Merge pull request #1 from djromero/escape-to-clear-log

Escape to clear log