Flip rotate

This branch introduces some changes in the interest of generating more training data:

* `FlipTransform` has been updated to flip a template's points in addition to its image.  An initializer also adds an abbreviation with the correct indices to swap for the MUCT point set.
* `RandRotateTransform` rotates an image and its points between a specified range.  To facilitate an algorithm like `Dup(5)+Expand+RandRotate`, `File::append` has been modified to append points/rects instead of overwriting them.
IMO that's a pretty serious change in behavior which should at least have a boolean variable that defaults to keeping just the flipped image, or it should be a separate transform entirely.

I'm guessing this is to construct additional training instances? Perhaps it'd be better to introduce a meta transform that passes along a template unmodified and also the template projected through an arbitrary transform?