The module registry throws an exception when trying to register a module
instances if an instance is already registered under the same name. This
backfired in love.thread when requiring love-modules.
Module::registerInstance() registers a module instance which can later
be retrieved using Module::getInstance().
registerInstance() is called in luax_register_module().
getInstance() expects the full name (as returned by Module::getName())
of the requested module.
Alex Szpakowski
vrld