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/sys/unix/readdirent_getdents.go

@@ -0,0 +1,12 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build aix dragonfly freebsd linux netbsd openbsd
+
+package unix
+
+// ReadDirent reads directory entries from fd and writes them into buf.
+func ReadDirent(fd int, buf []byte) (n int, err error) {
+	return Getdents(fd, buf)
+}