Called to initialize the plugin, when the user activates it (must not be @c NULL)
Array of plugin-provided signal handlers @see PluginCallback
Called when the plugin is disabled or when Geany exits (must not be @c NULL)
plugins configure dialog, optional (can be @c NULL)
Called when the plugin should show some help, optional (can be @c NULL)
Callback functions that need to be implemented for every plugin.