Implement test optimization for Groovy

Implement test optimization for Groovy code for Clover-for-Ant and Clover-for-Maven2 plugins. Currently it always runs all tests.

Tricky part in Ant:

1) Ant <junit><batchtest> batchtest collects the included resources from any number of nested Resource Collections. It then generates a test class name for each resource that ends in .java or .class. It means that *.groovy files will be ignored. However, we could use *.class files, for example:

<fileset dir="${build.dir}">
    <include name="**/*Test.class"/>
</fileset>

Then we can run both groovy and java unit tests from Ant.

2) But then if we try to use *.class inclusion pattern with <clover-optimized-testset>, for instance:

<clover-optimized-testset>
    <fileset dir="${build.dir}">
        <include name="**/*Test.class"/>
    </fileset>
</clover-optimized-testset>

then Clover (BaseCloverOptimizedTestSelector + BaseCloverOptimizedType) will try to "guess" source file name by renaming Foo.class to Foo.java. As a consequence it is unable to find Foo.groovy file...

Tricky part in Maven:

t.b.d.

Tricky part with TestSuites:

Known problem. Clover does not optimize TestSuites. Thus user cannot use any tests suites. It means that also Groovy "AllTestSuite" runner cannot be used for test launching.