Have a more detailed way of changing rect size.

* timestream/manipulate/pot.py (rect, increaseRect, reduceRect): We can now
define the amount of pixels to change for each side of the pot rectangle.
Fixes for the derandomization logic.

* timestream/manipulate/pipecomponents.py (DerandomizeTimeStreams): Adjust the
size of the pot rectangle to fit the maximum rectangle size. Make sure we catch
the exception when a timestream has no timestamp
* util/derandui.py (_derandomize): Give the user the option of selecting where
she wants to put the derandomization output.
Add a progress bar to derandomization.

* util/derandui.py (_derandomize): Set progress bar to visible during
derandomization.
* util/derandui.ui: Add progress bar to UI.