Delay initialization of some config

### Delay of namespace initialization

This is needed to allow users to modify $smwgNamespaceIndex, which
is used to determine the value of the namespace constants.

This breaks setting smwgNamespacesWithSemanticLinks directly in LocalSettings.
Instead it will need to be set in a delayed callback, as follows:

$GLOBALS['wgExtensionFunctions'][] = function() {
    // do stuff with $GLOBALS['smwgNamespacesWithSemanticLinks']
};

### Further delayed initialization

smwgNamespace and smwgScriptPath now also get initialized later. There is no
other config building on those, so no compatibility break like the namespace related
one is introduced for this. Additions to wgResourceModules are also delayed.

Change-Id: Ic12b8b391b07aa35fa2ffa1074cf3b67c265e2ba