[testsuite] Add lots of tests to ensure that the query optimizer is properly analyzing all possible types of XQuery expressions. Extend XQuery test suite to support tests on index usage optimizations (if @test:stats annotation is present).
[bugfix] XQuery optimizer failed to analyze enclosed expressions in attributes, default clauses of switch and typeswitch, and map constructors. This severly limited the performance of those expressions.
Add optimizer tests to default tests.
Merge remote-tracking branch 'upstream/develop' into feature/optimizer-fixes
Merge branch 'feature/optimizer-fixes' into develop