import_fdsnws_eq: Get the XML, dump some YAML
Prepares a dictionary with the interesting things found by reading the QuakeML file served for a given event. - If no focal mechanism is present, return None in those components of the dictionary; YAML serialises these as 'null'. - Parse FM XML object for all six nodal plane angles. - Catch float conversion problems by omitting output of these. - Check event id looks okay. - If called from command line, report outfile name.