TODO:

idl: 
      possibly change Value.idl interface to return a value union. [Bill]
cspi: 
      API change required if above IDL change is made.

libspi: 

      Change the weird string-hash event matching to something sane,
using GQuark. [Bill]

      Merge the DeviceEvent and KeyEvent structs to avoid the bogus casting of
these back and forth.

      Complete implementation of support for RelationSet and StateSet, and
export to cspi. 

      Complete and test the pre-emptive key API so that we don't always do
AnyKey grabs. [Bill]

test:

      Add tests for AtkTable, and add table elements to the test window.