SemanticMediaWiki.hooks clean-up

Added:
- SMW\MediaWiki\Hooks\ResourceLoaderGetConfigVars;
- SMW\MediaWiki\Hooks\GetPreferences;
- SMW\MediaWiki\Hooks\SkinTemplateNavigation;

Removed:
- `onParserTestTables` which was never used
Careful with starting class names with verbs, even if it is in the Hooks NS