Cycles: merge of changes from tomato branch.

Regular rendering now works tiled, and supports save buffers to save memory
during render and cache render results.

Brick texture node by Thomas.
http://wiki.blender.org/index.php/Doc:2.6/Manual/Render/Cycles/Nodes/Textures#Brick_Texture

Image texture Blended Box Mapping.
http://wiki.blender.org/index.php/Doc:2.6/Manual/Render/Cycles/Nodes/Textures#Image_Texture
http://mango.blender.org/production/blended_box/

Various bug fixes by Sergey and Campbell.
* Fix for reading freed memory in some node setups.
* Fix incorrect memory read when synchronizing mesh motion.
* Fix crash appearing when direct light usage is different on different layers.
* Fix for vector pass gives wrong result in some circumstances.
* Fix for wrong resolution used for rendering Render Layer node.
* Option to cancel rendering when doing initial synchronization.
* No more texture limit when using CPU render.
* Many fixes for new tiled rendering.

intern/cycles/blender/blender_python.cpp

@@ -80,6 +80,8 @@ static PyObject *create_func(PyObject *self, PyObject *args)
 	/* create session */
 	BlenderSession *session;
 
+	Py_BEGIN_ALLOW_THREADS
+
 	if(rv3d) {
 		/* interactive session */
 		int width = region.width();
@@ -91,7 +93,9 @@ static PyObject *create_func(PyObject *self, PyObject *args)
 		/* offline session */
 		session = new BlenderSession(engine, userpref, data, scene);
 	}
-	
+
+	Py_END_ALLOW_THREADS
+
 	return PyLong_FromVoidPtr(session);
 }
 
@@ -136,9 +140,13 @@ static PyObject *draw_func(PyObject *self, PyObject *args)
 
 static PyObject *sync_func(PyObject *self, PyObject *value)
 {
+	Py_BEGIN_ALLOW_THREADS
+
 	BlenderSession *session = (BlenderSession*)PyLong_AsVoidPtr(value);
 	session->synchronize();
 
+	Py_END_ALLOW_THREADS
+
 	Py_RETURN_NONE;
 }