nodes: moved matrix input on "video input" elsewhere

Rather than plugging a matrix into the video input node, the matrix is now
multiplied by the video input using a math node. This is probably more
sensible from a user perspective.

This also means the renderer is tolerant of texture sizes that are not equal
to the sequence size, however most nodes will downsample the texture to the
sequence size (and if not, it will be downsampled once it is cached). Textures
will still *always* be in reference space and the sequence's format. This seems
like the best compromise between backend and frontend congruity.

app/node/factory.cpp

@@ -25,7 +25,7 @@
 #include "block/clip/clip.h"
 #include "block/gap/gap.h"
 #include "block/transition/externaltransition.h"
-#include "distort/transform/transform.h"
+#include "generator/matrix/matrix.h"
 #include "input/media/video/video.h"
 #include "input/media/audio/audio.h"
 #include "input/time/timeinput.h"
@@ -141,8 +141,8 @@ Node *NodeFactory::CreateInternal(const NodeFactory::InternalID &id)
     return new ClipBlock();
   case kGapBlock:
     return new GapBlock();
-  case kTransformDistort:
-    return new TransformDistort();
+  case kMatrixGenerator:
+    return new MatrixGenerator();
   case kVideoInput:
     return new VideoInput();
   case kAudioInput: