Stabilize the api

[jontze]

Improve the api parameters and functions.

• Allow all kind of Vector/array of strings 8043e61 ( Vec<String>, Vec<&str>, [String], [&str] )
• Propagate more errors that lead to a panic before 4c62498
• Allow every rust string type as parameter instead only a reference b10f7a8
• Add more error types e03b5d6
• Remove some remaining println statements 095854f
• Use rustls-tls to avoid to depend on the openssl 649377c
• Add more commen traits to public data structs 5bb28ee
• Check all points here https://rust-lang.github.io/api-guidelines/checklist.html