Tkintertable

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* restored Filtering.py, filtering works ok
* more improvement to auto resize cols, now checks currrent col sizes
* fixed model.save() method
* added ability to save table, add rows to popup menu
* fixed delete cells button binding
* cell font preferences now uses available fonts from os
* removed unused prefs from dialog

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* add_Column method fixed
* Added ability to align cells left right or center
* Fixed problem of sort order lost when deleting rows
* Sort in descending order works correctly
* Fixes to plotting, but needs reworking or removal
* Added setSelectedCells method so a block of cells can be selected
* Improved text fitting in cells
* Automatic resizing of columns improved