Moved the opacity member to the graphic2d class.

#33
Added the initial map loading functionality.

- Still need to add loading hooks.
- Still need to add property hooks.

#3
Modified how grid lines are handled so they're only constructed if/when drawgridlines is set to true.

#37
Verified graphic is valid prior to adding it to the Grid.

#38
Made the SquareTileMap load its data asynchronously.  Also added bindings to tie into the async loading.

#36
#35
Modified the JSON loader to return preloaded information that can be used to learn information about the map that's being loaded.

- This also involved adding an event that can be bound to to determine percent loaded.
- The percent loaded change ties into the SquareTileMap's asynchronous loading management.
- Added a helper file to make all the async assets more useable.

#3
Updated the map loading sample to utilize the new async loading (to prevent the browser from freezing).

- Shows detailed information about the map that's being loaded.

#3
Added property hooks to JSON map loading.  Property hooks can be used to modify tiles as they're loaded onto the map by either adding children, hiding or building other objects based on their loaded data.

#3
Compiled all changes into the auto generated files.