Replace third party portmapper with leightweight own implementation

Currently, we are using this portmapper for exposing our server. We have some problems with this library:

• It has not been maintained for years.
• It is a normal program behavior to write exceptions to the log (this has already led to irritations with some of our users).
• It does not check the router responses and therefore throws unchecked exceptions.
• It PCP implementation is incompatible with AVM routers.
• It is very "noisy" (i.e., it sends its discovery requests to dozens of IP addresses on the network)
• It starts its own UPD servers and does not use the already existing one from drasyl.