Populate first column when adding a timestream

* timestream/manipulate/pot.py(numPots): New property that returns the number of
pots in a ImagePotMatrix.
* util/derandui.py (WindowTS): New class that contains the relation between
TimeStreamTraverser instance and the csv table. Its easier to have them together
as they change at the same time in the GUI.
(onClickTimeStreamList): Check to see if TimeStreamTraverser has all relevant
information before we add to list. We use the new WindowTS here. Ignore clicks
to the last row in the tslist.
(selectRowTS): Incorporate ddm in when selecting row in tslist.
(DropDownMenu, DropDownMenu_TS): New classes that contain menu widget for csv
table headers. They will contain all logic that has to do with filling the
column under the header.
* util/derandui.ui: Initialize the csv with 2 columns and one row, No headers.
Replace DropDownMenu with QComboBox

* util/derandui.py (QComboBox_TS): New class replacing DropDownMenu and friends.
(DropDownMenu, DropDownMenu_TS): Removed Classes
Change first column when metaid are selected

* util/derandui.py (onChange): New Method that will change the first column on
metaid selection.
Clean the first column when add/removing timestreams

* util/derandui.py (onClickTimeStreamList): We clean all the first column if we
end up with a _activeTS == None
(onChange): Ignore the signal if we have no self._tst
Remove _timestreams

We keep track with the qtlist.
* util/derandui.py: Store the TimeStreamTraverser in list item data.
* util/derandui.ui: Remove the hidden column.
Adjust the csv upload logic.

* util/derandui.py (selectCsv): It now fills the csv data from the second column
on.