Change mzml names to accessions?

We had a problem with some data in which the mzml parser couldn't find the name 'mslevel' in one of the scans. The pymzml documentation says we can use either names or accessions. The accession for mslevel is:
MS:1000511
So we should perhaps change the loader to use this as I *think* this will always be present...

Should be a case of changing one line...