Removing the BSVariableRegistry and instead making public static vars in BSApp for...

Removing the BSVariableRegistry and instead making public static vars in BSApp for the necessary inter-linking modules

* Api.php: No longer use BSApp::registry() but rather just the cvars
* App.php: Make the ivars cvars so we no longer need singleton stuff
(BSApp::_instance): Removed
(BSApp::registry): Removed
(BSApp::load_module): Removed, just directly instantiate now
(BSApp::required_modules): Removed
(BSVariableRegistry): Removed
* Input.php: Use cvars instead of the BSApp::registry()
* Installer.php: ditto
* Mail.php: ditto
* Pagination.php: ditto
* Template.php: ditto