Transform Toy Updates

[gleicher]

• code cleanup
• step (animated), step back, begin end (full controls)
• specific demonstration selected from URL
• fit better into 16x9 (code on side), option for place for talking head
• general affine transformations
• turn off the interface
• easier to type in examples
• better integration into workbooks

[gleicher]

We should probably plan out the set of these. We might also want to have a separate/new repository to better organize these.