net-config: start split out matching and parsing logic

Move this to src/share/net-util.c, so it can be used elsewhere.
rtnl: add support for routes
update TODO
bus: dbus-daemons' access messages are a bit too verbose
bus: support implicit serialization of strv string arrays within vtables
bus: make it easy to serialize C99 bools and uids/gids/pids via vtable properties
event: add some well-defined priority values of event sources
machined: simplifications
user-sessions: modernizations
localed: mark bus properties as change emitting

Otherwise sd_bus_emit_properties_changed() will refuse sending out
change signals
logind: port logind to libsystemd-bus
logind: fix serialization of ListSeats() bus call
logind: expose linger state on User object
net-util: don't use libudev

Should fix linking with old toolchain.
bus: allow that if the destination pointer in sd_bus_message_read_basic() is NULL we skip over a field
bus: add sd_bus_message_skip() to skip over multiple fields
bus: update bus_map_all_properties()
bus: support entering containers without specifying the type

On request om Tom Gundersen...
bus: delete some now used dbus1 code
update TODO