Replace SubclassFactory with a RegisterFactory

[oerc0122]

Description of work

• Replace SubclassFactory with a classic RegisterFactory to avoid metaclass magic, allow effective ABCs and explicit inclusion (i.e. not including Converter as an IJob and thus making a non-instantiable object a key) and naming (including multiple names for the same thing).
• Add UCDict class for case-insensitive dictionary keys.
• Add Dummy IJob child to account for ABC working properly.

PR is broken down since it is a large number of files touched (though small changes):

• First commit implements the factory and UCDict
• Middle commits affect each historic SubclassFactory
• Last commit makes changes necessary for code to function

NB. Converters are registered in both IJob and Converter as was historical.

Fixes
Part of the motivation for this is to support a factory-like mechanism for GUI Widgets from Descriptor types.

To test
Standard tests should run.

[MBartkowiakSTFC]

The changes did not affect anything major, as far as I can tell. However, the way the class names have been converted to uppercase characters has been interfering with combo boxes.

So far, I have found the following problems:

1. The instrument definitions used to set the q vector generator type to "SphericalLatticeQVectors". As this has been replaced with "SPHERICALLATTICEQVECTORS", the combo box remains set to "CIRCULARLATTICEQVECTORS" when an instrument profile has been selected.
2. When a new plot is created, the plotter type used for the plot is "Single", but the combo box shows "GRID". Also, it is possible to switch the plotter type to "TEXT" or "VECTORS", which should normally be disabled.