drag-action: fix press coords transform with drag_handle

When setting a drag handle, transform the original press
coordinates using the drag handle as reference instead of the
associated actor.

This causes the initial misplacement of drag handle in
example/drag-action when holding down the Shift key: the handle
gets placed at the main actor origin on the first drag event,
instead of following the mouse pointer.

All subsequent motion events already use the right actor when
transforming the coordinates, thus they are not affected.

https://bugzilla.gnome.org/show_bug.cgi?id=681746
Fix clutter_table_layout_pack row/column count incrementation.

When appending (with a negative row/column parameter), the row/column
count should be incremented by 1, not 2. This also fixes layout errors
when using column/row spacing: The amount of extra space required was
calculated incorrectly due to the wrong column count.

https://bugzilla.gnome.org/show_bug.cgi?id=679990
Implemented FUEL entries to Assamese translation
gesture-action: add allow-none annotations to getters

https://bugzilla.gnome.org/show_bug.cgi?id=681648
gesture-action: add _get_motion_delta()/_get_velocity()

Add some accessors to simplify common tasks for GestureAction users:

• clutter_gesture_action_get_motion_delta() to get the delta
  on the X and Y axis in stage coordinates since the last motion
  event, and the scalar distance travelled;

• clutter_gesture_action_get_velocity() to get an estimate of the
  speed of the last motion event along the X and Y axis and as a
  scalar value in pixels per millisecond.

https://bugzilla.gnome.org/show_bug.cgi?id=681648
pan-action: add PanAction, to handle panning in scrollable actors

PanAction is a GestureAction-subclass that implements the panning
concept for scrollable actors, with the ability to emit interpolated
signals to emulate the kinetic inertia of the panning. PanAction provides:

• pan signal, notifying users of the panning gesture status;

• pan-stopped signal, emitted at the end of the interpolated phase
  of the panning gesture, if enabled;

• pan-axis property, to allow constraining the dragging to a specific
  axis;

• interpolated property, to enable or disable the inertial behaviour;

• deceleration property, to customize the rate at which the momentum
  of the panning will be slowed down;

• acceleration-factor property, applied to the inertial momentum when
  starting the interpolated sequence.

An interactive test is also provided.

https://bugzilla.gnome.org/show_bug.cgi?id=681648
Update POTFILES.in
Updated Spanish translation
Updated Polish translation
Updated Lithuanian translation
Updated Galician translations
Updated Belarusian translation.
Updated Polish translation
x11/device-manager-xi2: Put XIPointerEmulated under conditionals

There are a couple of debugging messages using XInput 2.2 symbols
unconditionally, and it breaks builds on older systems.

https://bugzilla.gnome.org/show_bug.cgi?id=683219
brightness-contrast-effect: Don't actually run if it will have no effect

Don't run the shader and redirect to an FBO if it won't actually do anything.
This saves us on resources a ton.

https://bugzilla.gnome.org/show_bug.cgi?id=683066
gesture-action: Add API for cancelling a gesture

and getters for sequences and devices of current points. It can be
used for accepting and rejecting sequences for system-wide gestures.

https://bugzilla.gnome.org/show_bug.cgi?id=683090
actor: Remove existing implicit transition if duration is 0

When changing an implicit transition mid flight we may end up with an
easing state with a duration of zero milliseconds; this leads to the
implicit transition machinery setting the final state directly onto the
actor. If there is a running transition, though, we need to remove it
from the transitions table, otherwise it will keep running.

This regression happened when the update_transition() internal function
was merged into the create_transition() one.

Tested-by: Lionel Landwerlin <llandwerlin@gmail.com>
Include cogl/cogl-egl.h from clutter-egl-headers.h

Since Cogl version 1.11.2, Cogl no longer includes the EGL headers
from cogl.h if COGL_ENABLE_EXPERIMENTAL_2_0_API is defined. Instead
the application needs to include cogl-egl.h so that we can avoid
polluting the global namespace with X defines. Clutter defines the 2.0
define in its configure.ac and it is relying on Cogl to include the
right EGL header in clutter-egl-headers.h so we need to change which
header it includes.
Add interpolation for matrices

Interpolating between two transformations expressed using a 3D matrix
can be achieved by decomposing the matrices into their transformations
and do a simple numeric interpolation between the initial and final
states, like we do for other data types.

Luckily for us, the CSS Transforms specification from the W3C provides
the decomposition algorithm, using the "unmatrix" code taken from the
book "Graphics Gems II, edited by Jim Arvo".

Once the matrices have been decomposed, we can simply interpolate the
transformations, and re-apply them onto the result matrix, using the
facilities that Clutter provides for interpolating between two known
GTypes.
actor: Make :transform and :child-transform animatable

Now that we can interpolate between two matrices, we can mark the
matrix-based property as animatable.