Move typedefs before public structs to work around gnome bug #581525
Use single include for c_glib.
Use gtk-doc for thrift_c_glib
Add gtk-doc comments to c_glib code.
THRIFT-1879 Add GObject Introspection support
Add Vala bindings for c_glib
Register c_glib enumerations with GType using glib-mkenums