General D-Bus support

TpProxy — base class for Telepathy client proxy objects
TpProxy D-Bus core methods — The D-Bus Introspectable, Peer and Properties interfaces
TpProxy Telepathy Properties — The Telepathy Properties interface
D-Bus utilities — some D-Bus utility functions
Manipulating a{sv} mappings — Functions to manipulate mappings from string to variant, as represented in dbus-glib by a GHashTable from string to GValue
TpProxy subclasses and mixins — Providing extra functionality for a TpProxy or subclass, or subclassing it