Revision 1968

Enable the experimental attribute editing again and introduce a
command line switch to actually activate it

* Thuban/UI/main.py (options): New. Container for options set on
the commmand line
(main): Add the --enable-attribute-editing flag.

* Thuban/UI/identifyview.py (IdentifyView.__init__): If attribute
editing is enabled use the grid ctrl which allows editing of the
values

* Thuban/Model/transientdb.py (AutoTransientTable.write_record):
New. Just delegate this to the underlying table.