SimpleSingleRangeNextTest: add overflow tests
SimpleSingleRangeNextTest: rename tests
Helper: add new sinkTest helpers

- Create a SinkTestCase from an IDesign.
- Create a SinkTestCase from parameters.
Added AdvancedSetValueTest
SimpleSingleRangeNextTest: bool with limits
Added RangeTestCase

This class is fully functional, but it is difficult to utilize at the
moment, because design space and design don't always agree on legal
values in v0.5. I'm getting tired of these classes cluttering up my
untracked files. So here they are.
FixedNumericTest: add javadoc
Deprecated RangeTestHelper
Removed RangeTestHelper

This class (or an equivalent) might make a come-back later, when
RangeTestCase is usable.
TypeMismatchTest: add javadoc