RC1 for 2nd milestone for "R5N (2021-02-038)"/Go implementation

[Bernd Fix]

Dear GNUnet community,

the Go implementation for the second Milestone is nearing completion; 
nearly all points for "2. Core data structures and processes" are 
implemented.

The implementation follows the specification (lsd0004) as closely as 
possible (the spec itself is work-in-progress), so adjustments and 
corrections in the spec will have to be worked on at a later time.

Open ends are mostly in the underlying transport framework (which is not 
part of the milestone, but required for integration tests). Due to the 
limited availabilty of a testbed don't expect the code to run flawlessly 
yet, but at least it compiles and successfully runs unit tests ;)

As usual you can find the current version of the source code at 
https://git.gnunet.org/gnunet-go.git/

Happy hacking,
Bernd.