2012-09-16

Added interaction between bubbles. Fixed some bugs.

Changes:

Class: Calculate
- Added new interaction method calculateBubbleBubble() that calculates
the contextual interaction between bubble and bubble.
- If it finds that the bubble is within the x and y parameters of
touching any other bubble, will calculate the combination for a new
bubble, and destroy the secondary bubble.
- As you can see, the Calculate class will hold methods for
calculating every possible combination of objects. The contextual
relationships are defined here.

Collision rendering fixed due to Arc2D taking the x and y inputs of
the arc as the leftmost and topmost pixels, rather than the HTML5
Canvas API which defines the x and y parameters as centers of circles.