Allow giving names to fixture filter data groups and bits

[rachelnertia]

GuiControls(b2Filter&) will be passed a structure containing a string for each named bit and each named group. I'm not sure where that data will come from, though. Perhaps it could be loaded from a json file.

For now, the data will belong to the application and ApplicationStateContext will store a reference to it. It will be used in the editor and possibly in logging.