cairo: Add some missing 1.12.x and pre 1.13.x bindings
gtk+-3.0: Add a11y.h header to accessible objects

Based on patch by Peter Vagner

Fixes bug 735265
gstreamer-1.0: remove owned to floating reference parameters

Commit 6296d34707 (bug 730983) added the owned
keyword back without any reason.

Fixes bug 738012
gio-2.0: Update from 2.42 branch
webkit2gtk-web-extension-4.0: add delegate for EventTarget listener
webkit2gtk-web-extension-4.0: add missing *-custom.vala
gtk+-3.0: add some default values
glib-2.0: set cname for SearchFunc
pango, pangocairo: update to git master

This adds a lot of nullability fixes from bug #731022
gtksourceview-3.0: remove from GIR_BINDINGS

gtksourceview distributes bindings upstream these days, no need to
keep the deprecated copy in the Vala repository updated.
gtk+-3.0: Update to 3.15.0
bindings: Update GIR-based bindings
fix typo for non-constant field initializers
Infer array length of inline allocated arrays

Fixes bug 644046.
Add test for commit 0f0bca7e0519
webkit2gtk-4.0: Update to 2.7.1
bindings: Update GIR-based bindings
gtk+-3.0: Update to 3.15.1+89e12495
Use .ascii_up() instead of .up()

Fixes bug 739393
posix: add IPPROTO_* bindings