gstreamer: support Gst::Bus#set_handler

But it causes SEGV... We should not use GVL lock/unlock?

[ruby-gnome2-devel-ja]

Reported by Takashi Nakajima. Thanks!!!
gstreamer: extract common code
gstreamer: sample streams
Merge pull request #159 from ted-n/gstreamer-samples

gstreamer: sample streams

Patch by Takashi Nakajima. Thanks!!!
gstreamer: add GstController loader

[ruby-gnome2-devel-ja]

Suggested by Takashi Nakajima. Thanks!!!
goocanvas: use protected instead of __send__
glib2: define types for mark/free
glib2: add mark/free functions change API
goocanvas: disable GC while creating canvas

GC is too slow for many objects environment...
goocanvas: add missing GI path
goocanvas: migrate to GI based bindings
goocanvas: sample/goocanvas-gi.rb -> lib/
goocanvas: remove "-gi" suffix
goocanvas: use mark function instead of keeping references
goocanvas: revert reducing # of objects

Because we improve speeds! It was GC related.
goocanvas: remove reed note
goocanvas: use goo/ directory
gi: support boxed type loading

But n_fields and n_methods aren't implemented yet.
clutter: support Color.new() with Clutter 1.10.x
clutter: add Color.parse convenience method