This required the implementation of a new method on BaseDatatypeTester.
dynamic_assert_equal is overridden by floating point datatypes, and
instead uses TestCase.assertAlmostEqual.
* NumberDatatype
* StringDatatype
_raise_serialization_value_error_data is now a classmethod instead of a classmethod.
Tests for MIN and MAX number values of NumberDatatypes have been made more abstract.
TEST_DATA_* has been removed from variable names. Sometimes it can get a little too rediculous with these var-names, don't you think?