* Reduce Nim 1.6 compiler warnings/hints for Fluffy and Nimbus proxy
Mostly raises Defect removals, TaintedString removal and some
unnecessary imports.
Also updating the copyright years alongside.
* Further reduce Nim 1.6 compiler warnings/hints for Nimbus
Default the network key will be taken from a network key file
instead of randomly generated on each run. This is done because
the data that gets stored in the content database is dependant on
the network key used, as the node id is derived from this.
Kim De Mey