Source files clean up
UIDataViewList: Introduce void ctor
Add resources cfg template file
VisualUnitTest: Introduce default state modification methods

* Introduce getters for the default callbacks used during init in
::SetUp; these can go along with the new methods for clearing the
registered callbacks storage to customize state further.

* Introduce window flags getter/setter for ez init when all you need
is a bit of tweaking from the default rendering state.
Gradient: Fix margins bug recently introduced (tex cache)

I had forgotten to account for local margins, and thus the
relative to absolute coordinates became out of sync. The red border
color we set in case of this kind of err really paid off for
helping visualize this bug fix!

* Use resource search paths cfg for GradientTest.
* Use a different color for secondary gradient test
object to help make it stand out.

* Introduce Margins test; uses an emulation of the bug sample
caught from TTcards to verify fix.