Invalid window dimension crash
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burntsushi5
PyTyle crashes and takes a screenful of managed windows with it when a _master_increase/decrease is performed which changes the width/height of a window to < 0.
To reproduce: With at least one slave window opened, repeatedly increase the size of the master window until the slave window disappears.
Patch for horizontal and vertical tilers, other tilers probably have the same problem and still need to be fixed