Add initial Keybase Chat support (#877)

* initial work on native keybase bridging

* Hopefully make a functional keybase bridge

* add keybase to bridgemap

* send to right channel, try to figure out received msgs

* add account and userid

* i am a Dam Fool

* Fix formatting for messages, handle /me

* update vendors, ran golint and goimports

* move handlers to handlers.go, clean up unused config options

* add sample config, fix inconsistent remote nick handling

* Update readme with keybase links

* Resolve fixmie errors

* Error -> Errorf

* fix linting errors in go.mod and go.sum

* explicitly join channels, ignore messages from non-specified channels

* check that team names match before bridging message

vendor/golang.org/x/crypto/ssh/messages.go

@@ -97,6 +97,36 @@ type kexDHReplyMsg struct {
 	Signature []byte
 }
 
+// See RFC 4419, section 5.
+const msgKexDHGexGroup = 31
+
+type kexDHGexGroupMsg struct {
+	P *big.Int `sshtype:"31"`
+	G *big.Int
+}
+
+const msgKexDHGexInit = 32
+
+type kexDHGexInitMsg struct {
+	X *big.Int `sshtype:"32"`
+}
+
+const msgKexDHGexReply = 33
+
+type kexDHGexReplyMsg struct {
+	HostKey   []byte `sshtype:"33"`
+	Y         *big.Int
+	Signature []byte
+}
+
+const msgKexDHGexRequest = 34
+
+type kexDHGexRequestMsg struct {
+	MinBits      uint32 `sshtype:"34"`
+	PreferedBits uint32
+	MaxBits      uint32
+}
+
 // See RFC 4253, section 10.
 const msgServiceRequest = 5