GdkCursor: Don't leak a cairo surface

The function gdk_cursor_new_from_pixbuf creates a cairo surface
to pass to its backend implementation, but doesn't destroy it
afterwards.
https://bugzilla.gnome.org/show_bug.cgi?id=729670
gtk-demo: Make sure to clear the timeout when we stop it
win32: add more clipboard data checks to avoid crash

It may happen that the received clipboard data is empty, but
if it's of type image/bmp, gtk+ will crash:

gdk_property_change: 00030AD4 GDK_SELECTION image/bmp REPLACE 8*0 bits:
... delayed rendering
gdk_selection_send_notify_for_display: 00030AD4 CLIPBOARD image/bmp
GDK_SELECTION (no-op)
_gdk_win32_selection_convert_to_dib: 1252003C image/bmp

Program received signal SIGSEGV, Segmentation fault.
0x749a9f40 in msvcrt!memmove () from C:\Windows\syswow64\msvcrt.dll

Thread 1 (Thread 2248.0x1b34):
target=0xc07b) at gdkselection-win32.c:1292
at gdkevents-win32.c:3498
wparam=8, lparam=0) at gdkevents-win32.c:232
message=773, wparam=8, lparam=0)
    at gdkevents-win32.c:263
C:\Windows\syswow64\user32.dll
C:\Users\rugoosse\AppData\Local\virt-viewer\bin\libpangocairo-1.0-0.dll
wparam=0, lparam=-1687549457)
    at gdkevents-win32.c:248
C:\Users\rugoosse\AppData\Local\virt-viewer\bin\libpangocairo-1.0-0.dll

https://bugzilla.gnome.org/show_bug.cgi?id=728745
gdk/win32: VK_SNAPSHOT maps to GDK_Print

Also, I am not sure the above VK_PRINT -> GDK_Print mapping is
correct, but it doesn't hurt yet.

https://bugzilla.gnome.org/show_bug.cgi?id=686170
openbsd: properly set len for gtkmountoperation-x11

sysctl(3) is the correct way to get the lenght for len in this case.
Also drop unused headers and change style to match the rest of the file.
Fixed crash in GtkLockButton if a button with permission set to NULL is clicked.

https://bugzilla.gnome.org/show_bug.cgi?id=728992
GtkRecentChooserMenu: Set current uri before activating an item.

When activating an item using mnemonics GtkRecentChooserMenu does not select a
item before calling the item-activated signal thus
gtk_recent_chooser_get_current_uri() always return the last selected item
instead of the activated one.

Fixes Bug 495105 "Open recent file keyboard shortcuts do not work correctly"
gtk-demo: Fix images demo

The incremental loading was broken by GtkIconHelper - queuing a
redraw is no longer sufficient to cause GtkImage to redraw with
the new pixbuf contents.
Pointed out by Jasper St. Pierre.
GtkColorChooserWidget: Redraw swatches when selection changes

When selecting a swatch in a GtkColorChooserWidget the previously
selected swatch and the currently selected swatch are not redrawn. This
can leave the old swatch still marked with a checkbox even though a new
swatch has been selected.

Redraw the swatches after changing the selection.

https://bugzilla.gnome.org/show_bug.cgi?id=727487
applicationwindow: Properly unmap the menubar widget
a11y: Avoid a warning

The listbox row accessible code was giving warnings when
parent is NULL, at destruction time.
3.10.9
Bump version