Document that PluginLoader should be a singleton.
The kipi-plugins use the instance() method, and the constructor
sets up s_instance
.. this class should be a singleton,
but was not being used as one by Spectacle, leading to crashes.
The kipi-plugins use the instance() method, and the constructor
sets up s_instance
.. this class should be a singleton,
but was not being used as one by Spectacle, leading to crashes.