fix: fix cropped output when using Animate CC's camera

Animate CC's camera translates the mask of its parent (if there
is one) so that the mask's (0, 0) point coincides with its center,
and we do set a mask on it, so we end up with cropped output.

By setting the mask's position to (0, 0) just before a frame is
rendered, this problem is avoided.

Closes Herschel#1.

src/com/newgrounds/swivel/swf/SWFRecorder.hx

@@ -248,6 +248,11 @@ class SWFRecorder {
 		_window.stage.align = StageAlign.TOP_LEFT;
 		_window.stage.scaleMode = StageScaleMode.NO_SCALE;
 
+		// Reset mask position, in case someone changes it by doing something like parent.mask.x = ...
+		// The camera introduced in Animate CC does that, for example, which results in cropped output (#1).
+		_mask.x = 0;
+		_mask.y = 0;
+
 		if(recording) {
 			onFrameCaptured.dispatch( drawFrame() );
 		}