Refactor codebase before version 1.1 release

[ecj2]

These areas could use some work:

• Use a fixed length for iterating over mouse button arrays
• Add documentation where necessary
• Remove superfluous documentation where necessary
• Define mouse and keyboard arrays in the constructor
• Remove useless properties from object literals
• Default bitmap dimensions to undefined
• Replace on* with event listeners
• Replace window.* with *
• Remove event listeners when no longer needed