This improves on the previous commit for grouping and running Windows specific tests.  The previous implementation only worked for the default tests and not the precommit or function test definitions.

With this commit:

The following rules apply to the generation of content for test.xml by PrepTestNG:

- For the default test definition, if no group clauses have been specified and the platform is non-Windows and explicit Windows exclusion element is generated.
- For the default test definition, if group clauses have been specified a Windows exclusion element is generated if the platform is non-Windows and a Windows group clause has not been explicitly provided.
- The precommit and functional test definitions are always parameterized with an explicit Windows exclusion element if the platform is non-Windows.

Corrected and added to the test framework help generated in build.xml.

I have also cleaned up the formatting of the generated XML with reasonable indentation.

Reenabled TestStaticUtils.testRenameFileLockedTarget()