Move data validation into separate test suite

[rjmartell]

The GML test suite should be split into two separate test suites as follows:

1. Validate a GML schema against the standard rules for application schemas or profiles (all of the conformance classes in GML 3.2 are about this)
2. Validate a GML document (A.3)

This separation would allow for optimizations to enable validation of large GML documents or data streams, which is problematic at the moment.

[bermud]

Maybe not separate the tests but bring back the enchanted test for instance testing back into the main test suite.