Release Hush 2.0.1

[leto]

• Change configure version to 2.0.1
• Change version number in docs to 2.0.1
• Make sure CLIENT_NAME/etc thing that FiremartZ found says 2.0.1 too
• Update man pages via contrib/devtools/gen-manpages.sh, after changing configure version, make sure they say 2.0.1
• Update consensus rules to no longer talk to old nodes which do not have DPoW enabled at a prescribed block height
• Test latest code thoroughly, with txindex=0 and txindex=1
• Create git tag
• Add changelog notes to Github tag
• Make sure docs are updated
• Once tag is created, merge dev to master
• Ask FireMartz to create various binaries
• Ask Firemartz to update SWING gui wallet to latest hush binary