Spatial and Cluster tabs - Allow user to hide the whole spatial parameters section

[GoogleCodeExporter]

The calculations tree is given roughly half of the window height when
displayed, as the top half is occupied by the spatial options. 

The user can currently hide the individual spatial parameters and def
queries interfaces to free up some real estate, but it would be handy to
have a single button to hide/show them all in one go.  This will make it
easier to work with the calculations tree (or at least see more of it).

Original issue reported on code.google.com by shawnlaffan on 30 Jan 2010 at 10:51