Fix Typos

https://bugzilla.gnome.org/show_bug.cgi?id=695591
Remove crap
Add testcase for bgo#696762
Preserve argument order

Modify the solution used in d80d05f1 to use the begin_action_list variant
instead of _begin_action_hash.

Keep the _end_action_hash call; the calls can be used asynchronously and
_end_action_hash is better at collecting extra arguments.

https://bugzilla.gnome.org/show_bug.cgi?id=696762
Distribute test files
Prepare 0.20.2
Add rescan_control_points feature

This resolves bug https://bugzilla.gnome.org/show_bug.cgi?id=697314
Post-release version bump
Depend on vapigen >= 0.20 if g-i >= 1.36 is found
Clarify notification SEQ count behavior
Ensure NOTIFY message has a proper SID

SID must start with "uuid:" and has to have some value (the uuid
format was only specified in version 1.1 so that cannot be enforced).

https://bugzilla.gnome.org/show_bug.cgi?id=696289
Return 400 to NOTIFYs without NT or NTS header

We used to return 412 if the "NT" or "NTS" header field was missing.
Spec says we should return 400.

https://bugzilla.gnome.org/show_bug.cgi?id=698192
SEQ is supposed to be an uint32

https://bugzilla.gnome.org/show_bug.cgi?id=698125
Use unix CM as fall-back if netlink isn't there

Sometimes it might happen that netlink sockets aren't available on
runtime (QEmu for example).
Prevent C++ name mangling in examples
Fix compilation with -Wall -Wextra
Prepare 0.20.3
Post-release version bump
Fix gtk-doc warnings
Minor doc improvements