generalize mininode.py protocol versioning Fixes #2982 -- replace `overwintered` boolean argument to NodeConn constructor with a protocol version integer, so that adding Sapling (and beyond) will be easier.
generalize mininode.py protocol versioning Fixes #2982 -- replace `overwintered` boolean argument to NodeConn constructor with a protocol version integer, so that adding Sapling (and beyond) will be easier.