Decouple build-in schema

[metaodi]

• provide current schema as "plugin" of sorts
• Standard schema should contain only standard fields (?)
• maybe provide a default mapping per module (?)
• test with different instances

[mokko]

Let me know if you want to test in our instance. m.mengel@smb.spk-berlin.de. Or if I should test it for you.

[metaodi]

@mokko thanks for the kind offer. I currently have an instance I can use to test. But I will get back to you, once I figured out a better way to handle the schema. It's still a bit messy in my code 😄

[metaodi]

Note to myself: map_function is not a suitable way to handle the schema on a client level. Depending on the requested object, the desired schema changes.

I guess the library should return a sensible default schema for all modules and have a separate mechanism to change the schema based on the requested module (?).