Add packet field names to localization files.
Update specification data.

The specification data file can now be generated from the XML files
of the RESOL ServiceCenter (importer will be commited soon). Some
structural changes were applied to the specification data (e.g.
localization is now done using the I18N module, clean-up and unification
of the texts, units, ...). Tests have been adapted to these changes.
Add specification importer.

This importer searches an RSC installation for VBus specification XML
files, parses them, cleans them up, checks them for consistency and
then generates a specification data file from it.