Added named datapoint(s) support to theories, for #65.

Also refactored tests for internal elements of theory code into a matching internal test package en route, to make the two package heirarchies correspond properly.
Refactored FromDataPoints functionality to use SpecificDataPointsSupplier as a normal ParameterSupplier, by allowing ParameterSuppliers to take TestClasses in their constructors.

Also added a simple parameter supplier test case, since it appears there weren't any at all until now.
Minor further refactoring of Theory ParameterSupplier setup
Various improvements to named datapoint support after review.

Mostly revolves around validation of theory class configuration and some reorganising and tidy up of bits of testing code.
Added JavaDoc to DataPoints and FromDataPoints
Improvements to DataPoints/FromDatapoints annotation javadoc
Changed exception signature for assignments reflective methods to support older Java versions
Merge pull request #621 from pimterry/named-datapoints-#65

Added named datapoint(s) support to theories, fixing #65.