Adds a search engine to allow semantic queries directly from MW's standard search

This search engine will try to interpret the search term as a semantic query.

If succesful, the pages according to the query will be returned.
If not it falls back to the default search engine.

* Activate it by setting in LocalSettings.php: $wgSearchType = 'SMWSearch';
* Use $smwgFallbackSearchType to set the fallback search engine to be used if the
  search term is not a valid SMW query
Remove @file tags
Remove @ingroup tag from tests
Merge pull request #450 from s7eph4n/master

Adds a search engine to allow semantic queries directly from MW's standard search
Follow-up on 450

- Add SearchInPageDBIntegrationTest
- `testSearchForGeographicCoordinateValueAsTerm` needs Semantic Maps will fail for the SPARQLStore
- Minor Search clean-up
- Throw exception in case 'smwgFallbackSearchType' contains a invalid class
Merge pull request #496 from SemanticMediaWiki/follow-up-450

Follow-up on #450 / Add integration tests and clean-up
SearchTest minor clean-up
Tidy