Design Space tests use fake factory

The preset factories are faster. However, they should be tested
more thoroughly to ensure that they can really replace the real
factories during testing!
Testing factories

Added more thorough comparison of XML factories and
preset factories.
Removed redundant design space tests

The fake importers are already being tested elsewhere.
However, design space equality testing could be increased.
Increased API conformity

- Design now has a getSupportedParamIds method
- DesignSpace.nextEmptyDesign now produces a design that supports
    the proper parameter IDs, even if all are just None.
- Improved the related tests.
Fixed a test case name
Updated utilities

- Added a tiny function for getting the absolute ID of a parameter
    relative to a parent ID.
- Renamed "expandParameterScope" to "parent" since generating the
    parent ID is really what the function does.
Added a better factory for creating parameters

This factory is intended to make it easier to create parameters
both in code and when importing from XML.
Updated preset factories

The preset factories now use the new paramFactory function,
at least when "importing" the triangle configurations.