Rewrite command interfaces so that state is carried with undoable commands

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Right now the clients of an undoable command have to keep track of whether or 
not the command has been run previously (and should be added to the undo 
stack), should be run. This should be handled by the CommandHandler. If the 
execute() method has been called on a command, then the the executed state 
should be carried forward, so that the command handler does not execute the 
command again in the future, but only adds it to the command stack.

Original issue reported on code.google.com by delmyers...@gmail.com on 19 May 2011 at 10:00

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Original comment by delmyers...@gmail.com on 19 May 2011 at 10:01

• Changed state: Started

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Original comment by delmyers...@gmail.com on 20 May 2011 at 12:45

• Changed state: Fixed