create a new REST API

[michael-batz]

The current REST API has some problems, which should be fixed. As there are implementations, which already use the current REST API, a new API should be created and the current one should be marked as deprecated. The following problems should be solved in a new API:

• [ ] create a standard for returning results
• [ ] create a standard for handling errors
• [ ] create a detailed documentation with examples and example results