* Rename types:
* `ptr` types have no suffix (e.g. `ClientP` -> `Client`)
* normal object types hyve a `T` suffix, if needed (e.g. `Port` -> `PortT`)
* Constants also use CamelCase (UPPER_CASE can still be used).
* Make functions returning an error discardable
* Add missing return types for some functions.
Signed-off-by: Christopher Arndt <chris@chrisarndt.de>
