Oldschool fire effect with javascript + html5 canvas

Forked from https://github.com/oem/fire.

Refactored the Fire JS object to use prototype functions.

Added a default palette of 100 RGB triplets. Pass in another array as the 6th argument to the Fire constructor.

Ensured that the canvas[y][x] values remain within the range 0 to the number of colors.

Added burn() and out() functions to start/stop the fire. The timeout is now a property of the Fire object.

Added 7th Fire constructor argument, speed, used as the delay argument for the animation timeout.

Changed a lot of what happens inside interpolate_point(). Three new fire properties (cf1, cf2, focus) affect how much a color cools. The cf1 and cf2 properties determine the random cooling range, focus sets how much influence the original color has in determining the cooled color.

Moved the instantiation into the html file; fire.js is now just the object code.

Put a new look and feel into the HTML/CSS. Add a click handler to the canvas to allow the fire to be paused.