Improve docs and import structure

[f-brinkmann]

General

• pyfar version: 0.5.4

Description

• Unify documentation of classes, especially of magic functions like __init__
• Document functions contained in the class files, e.g., add or deg2rad
• Add information about handling complex time data to concepts/Arithmetic operations
• stop importing class moduls, e.g., pyfar.classes.coordinates

[artpelling]

Maybe add the sorting of import blocks to the list?

[f-brinkmann]

Do you mean the import ... statements in the Python files?

[artpelling]

Do you mean the import ... statements in the Python files?

Yes. Maybe that is unrelated, though...