Sine: synthesize and play a sine wave when touched

I'M SUPER PUMPED ABOUT THIS! IT WORKS! I learned a lot today!

Heavily based on:

http://www.cocoawithlove.com/2010/10/ios-tone-generator-introduction-to.html

with help from

https://ccrma.stanford.edu/~jsanchez/NSSpain.pdf

and

http://en.wikipedia.org/wiki/Sine_wave

but now I should be able to start abstracting it more and doing more
cool things with the tone renderer (although I've always loved the
pureness of sine waves.)