BGE: added bge.logic.{get,set}AnimRecordFrame functions

By using getAnimRecordFrame(), game developers have access to the frame
number used by the "Record animation" feature. This enables them to
record additional information in Blender's F-Curves and ensuring perfect
synchronization with the information already recorded by Blender.

The setAnimRecordFrame() can be used to change the frame number at which
animations are recorded, for example to introduce delays the recording that
do not require delays in the actual game/simulation run.

The getter/setter functions in KX_KetsjiEngine are not directly named after
property they access (m_currentFrame). I found "current frame" to be too
vague for a public interface, hence chose a more descriptive name.

Reviewers: moguri, hg1, campbellbarton, panzergame, aligorith

Reviewed By: panzergame, aligorith

Differential Revision: https://developer.blender.org/D1449

doc/python_api/rst/bge.logic.rst

@@ -337,6 +337,28 @@ General functions
 
    .. warning: Not implimented yet
 
+.. function:: getAnimRecordFrame()
+
+    Gets the current frame number used for recording animations. This
+    number is incremented automatically by Blender when the "Record
+    animation" feature is turned on.
+
+    :rtype: int
+
+.. function:: setAnimRecordFrame(framenr)
+
+    Sets the current frame number used for recording animations. This
+    number is automatically incremented by Blender when the "Record
+    animation" feature is turned on.
+
+    The frame number Must be non-negative, unless Blender has
+    :attr:`bpy.types.UserPreferencesEdit.use_negative_frames` enabled
+    in its user preferences. Only use non-negative numbers to be on
+    the safe side, unless you know what you are doing.
+
+    :arg framenr: The new frame number.
+    :type framenr: int
+
 .. function:: getExitKey()
 
    Gets the key used to exit the game engine