Distribute V1 legacy converters over the various client projects

[kiivihal]

Currently, the converters.py contains all the legacy converters. It would be better to have these as part of the client project so that you can make enhancements to these without the need for releasing a new version of Nave.

The Converters that are candidates for this are:

• ICNConverter
• ABMConverter
• TIBConverter

[hanswesterbeek]

@kiivihal Sure you don't want to move this to say 1.0.1?