function get(classType) {
	for (const name in cache) {
		if (
			(typeof classType === "string" && classType === name) ||
			cache[name] instanceof classType
		) {
			return cache[name];
		}
	}
}
returns the the plugin instance with the specified class type or registered name
@name get
@memberof plugin
@param {object|string} classType - the Class Object or registered name of the plugin to retreive
@returns {plugin.BasePlugin} a plugin instance or undefined