sofar: Refactoring - Roadmap for sofar 1.3.0

[f-brinkmann]

Suggested behavior:

• Add Sofa.convantion_status property that returns 'current', 'preliminary' or 'deprecated'

Reading SOFA files and creating Sofa objects

• Don't raise warnings if reading preliminary or deprecated conventions anymore. Thats cluttering the command line and is only important when writing
• Verify preliminary conventions. They should become stable at some point and errors should come up to be fixed. They are currently not verified. I forgot the reason for this.

Writing SOFA files

• Print information about custom variables with the information that users should check if they are necessary of information should be moved to standardized variables.
• Make printouts optional via a verbose flag
• Improve warning message for preliminary convention. Currently it is mentioned that conventions should be updated if possible. Which is actually not possible.

Updates in conventions

•  Update conventions, code, and testing once the conventions are released (see sofar: Upcoming changes in SOFA standard and conventions #112)

[ahms5]

Don't print names of custom variables. Thats cluttering the command line and is only important when writing

I'm using custom variables quite often and I never had the feeling that the text output is more useful for writing then reading. reading could also be useful for users, who have downloaded the files from somewhere. And yes it is cluttering the command line, but you can just set verbose to false and it wouldn't do it anymore.
In my opinion, we dont need to change the current reading behaviour.