Added option for loading custom config files via command line, and greatly enhanced error handling during loading of config files

When information is omitted from config files, defaults will be assumed from now on. Also, missing information does not break config file loading, but is properly checked.
Added directory for custom config files, and an exemplary config file for only loading the 'interactive' plugin (which in turn automatically loads the 'ros' plugin as a dependency)
Corrected config descriptions and changed a filename to a more appropriate one