Merge pull request #4873 from mind04/ed25519

update Ed25519 algorithm number and mnemonic and hook up algorithm 15 in the recursor

diff --cc pdns/dnssecinfra.cc
Simple merge

diff --cc pdns/pdns_recursor.cc
Simple merge

diff --cc pdns/pdnsutil.cc
Simple merge

diff --cc pdns/recursordist/Makefile.am
Simple merge

diff --cc pdns/recursordist/configure.ac
Simple merge