These are improvements I've made as necessary to develop Hockeypuck, an OpenPGP keyserver (https://launchpad.net/hockeypuck). The max armor line length was increased to 96 because some keyservers (SKS) will output armor with lines greater than 64 (the prior max). I've exposed packet.ReadEntity to support stream-parsing, useful for large SKS dump files. ReadKeyRing attempts to recover in the event of malformed data. Because many packet types are not yet supported, I added OpaquePacket to capture unsupported types for offline storage and later reparsing. R=agl CC=golang-dev https://golang.org/cl/6927044