GTK3: Use cairo for drawing

In GTK+ 3, the GDK drawing API (which closely mimics the X drawing API, which is itself modeled after PostScript) has been removed. All drawing in GTK+ 3 is done via cairo.

The GdkGC and GdkImage objects, as well as all the functions using them, are gone. This includes the gdk_draw family of functions like gdk_draw_rectangle() and gdk_draw_drawable(). As GdkGC is roughly equivalent to cairo_t and GdkImage was used for drawing images to GdkWindows, which cairo supports automatically, a transition is usually straightforward.

See https://developer.gnome.org/gtk3/3.9/gtk-migrating-2-to-3.html#id-1.6.3.3.8
Renamed darktable.gui->s to darktable.gui->surface
wb_presets: Adding whitebalance-presets for Pentax K-30 (extracted from DNG)
brush masks: sync payload and border in case of sharp edges
brush masks: minor fix
brush masks: fix another small rendering issue (gap)
Fix #9584: Show URL widget in facebook/g+ exporter
picasa: more s/picasa/google+/

Followup for 4130a7f15b2c8500ea914e817b17f6d843af0795
add darktable-cli to OSX package (untested)
Merge pull request #310 from LebedevRI/gtk3-03-use-cairo-for-drawing

GTK3: Use cairo for drawing
brush masks: more protection against buffer overflows
handle the case when user wants to pass --core arg to darktable-cli on OSX
[l10n] Swedish update, and corrected translation of "browser tab"
(should be "flik", not "tabb")
[doc] generate description of darktablerc
Merge pull request #312 from tuxuser/pentax_k30_wb_presets

Whitebalance Presets for Pentax K-30
wb_presets: minor cleanup
rawspeed: import svn r495
adobe_coeff: preliminary Panasonic DMC-GX7 matrix
rawspeed: Panasonic DMC-GH3 crop adjustment
correct a bug with drawn masks bauhaus combobox