multiqueue: do not reset last push result when pushing events

Use the last result as a default when pushing a item from a single queue,
otherwise the status gets reset to _OK when pushing events.

This causes problems when mistakenly activating a not-linked stream
that is being ignored upstream as it is not being used (adaptive
scenarios), it will make the multiqueue post a buffering message
on a pad that won't receive buffers

https://bugzilla.gnome.org/show_bug.cgi?id=725917
multiqueue: if buffering is disabled while buffering, post 100% message

Avoids stall waiting for buffering to reach 100%
queue: queue2: preserve last flow result when pushing events

Avoids mistakenly returning _OK when downstream is still
_NOT_LINKED on subsequent received pad pushes

https://bugzilla.gnome.org/show_bug.cgi?id=725917
queue2: remove unused variable

buffering_iteration was never used
queue2: if buffering is disabled while buffering, post 100% message

Avoids stall waiting for buffering to reach 100%
tee: use store_sticky events add add more logging

Use the pad as object for logging to get more context. Use
gst_pad_store_sticky_event() instead of sending the event. This avoids a warning
as here the pad is not yet linked and we actually don't want to send anyway.
pad: add debug helper for GstPadLinkReturn names

Add a helper like gst_flow_get_name() for GstPadLinkReturn. Use this in core.
API: gst_pad_link_get_name()
pad: simplify gst_pad_link_get_name() and fix Since marker

Has added benefit that compiler might warn if more values
are added to the enum.
docs: update plugin docs
docs: fix multiqueue docs for new template names foo_%d -> foo_%u

https://bugzilla.gnome.org/show_bug.cgi?id=726358
adapter: Adapt gst_adapter_copy() for bindings

This is done by introducing a new gst_adapter_copy_bytes() call that
returns a GBytes structure.

Fixes https://bugzilla.gnome.org/show_bug.cgi?id=725476
tests: multiqueue: fix eos count on test for not-linked case

From the test case:

/* This test creates a multiqueue with 2 streams. One receives
 * a constant flow of buffers, the other only gets one buffer, and then
 * new-segment events, and returns not-linked. The multiqueue should not fill.
 */

If one of the queues goes EOS and the other returns NOT_LINKED the stream
can be considerered EOS as a NOT_LINKED means that one of the branches has no
sink downstream that will block the EOS message posting.

https://bugzilla.gnome.org/show_bug.cgi?id=725917
win32: fix make-check by running 'make update-exports'
pad: forward return value from gst_pad_forward

Instead of ignoring the return value and always return TRUE pass the already agregated result back.
pad: actually return data.ret

The return value from gst_pad_forward() is the aggregated return value from the callback and the callback returns FALSE to continue iterating.
message: Add GST_MESSAGE_EXTENDED

https://bugzilla.gnome.org/show_bug.cgi?id=678402
devicemonitor: Add GstDeviceMonitor and related

Also add GstDevice and GstDeviceMonitorFactory
And add code to the registry to save them

https://bugzilla.gnome.org/show_bug.cgi?id=678402
gst: fix indentation
message, bus: do extended message types slightly differently

https://bugzilla.gnome.org/show_bug.cgi?id=678402
tests: add test for extended message types and gst_bus_timed_pop_filtered