added limit=None for all endpoint of ‘contacts’; added request parameter...

added limit=None for all endpoint of ‘contacts’; added request parameter ‘fields’ for endpoints ‘variables’ and ‘contacts’; introduced a comprehensive error message when wrong values are given for the parameter ‘fields’; output format of metadata from ‘search’ and ‘timeseries’ was adjusted to that from the metadata of endpoint ‘data’; removed helper methods for the independent endpoint ‘analysis’