v19
dbus/address: drop well-known name validation
dbus/address: introduce peer address abstraction
connection/dequeue: make error codes more finegrained
message: document API
message/header: use an explicit error code for missing FDs
protocol: add more validation helpers
iqueue: consider receipt of FDs during authentication a protocol violation
dbus/socket: extract input-handling into separate queue object
sasl: document API
connection: only send/receive FDs to peers who support it
dbus/socket: track FDs while pending in kernel buffers
message/test: fix on BE architectures
test: extend sasl tests
dbus/socket: hide skb object
subprojects: update to master