#125 intelligent window maximization

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This is a combination of the following patches:

http://sourceforge.net/tracker/index.php?func=detail&aid=1709305&group_id=35398&atid=413962
http://sourceforge.net/tracker/index.php?func=detail&aid=1683029&group_id=35398&atid=413962

A few bugs were fixed, some useless code removed, and updated so it applies cleanly to
svn revision 5053.

New commands/settings:

* MoveFree <UP|DOWN|RIGHT|LEFT> (moves the current window in the given direction until it
reaches another window border or the desktop border)

* Expand (enlarge the current window size with the same logic of the previous command)

* ResizeToPrevious (revert the window size to the dimension it had before the Expand command)

* session.screen<N>.autoArrange.vertically (boolean)

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intelligent window maximization