Updated location of the tutorial
adding @agmcleod changes + 'screencanvas' extension support

@see https://github.com/melonjs/melonJS/pull/190
Make `force` optional when calling `me.game.removeAll()`. This makes the function pseudo-safe to use from callbacks.
ticket #193 : removed the tutorial from the melonjs main branch now that it has a new home

@see https://github.com/melonjs/tutorial
few changes here and there on the 'screencanvas' extension support

I finally change the `vendorExt` to a private parameter (not publicized)
Add collision_test to illustrate performance improvements in ticket #103
Smaller smilies in collision_test. Gives a better view of what's happening with hundreds of entities colliding.
Disable audio on Mobile browsers (again) because it apparently cannot be fixed. Maybe the Web Audio API will help?
Added a `me.sys.isMobile` boolean flag, and added detection of BlackBerry and Windows Phone
[#164] Prevent TypeError with invalid `me.game.remove(null)`
[#196] Allow `alpha` and `volume` to be set to 0.

- Bonus: Fixed an error message!
ticket #196 : use explicit type check when checking the given parameter
use a regexp when checking for MSIE
Update me.Vector2d methods to return a reference to `this` for method chaining.

Example:
var vec = new me.Vector2d(
    Math.cos(Math.PI / 4),
    Math.sin(Math.PI / 4)
).scale(new me.Vector2d(16, 16)).floorSelf().negateSelf();

- Creates a new unit vector at 45 degrees.
- Scales the vector to 16 units.
- Floors the product.
- Negates the result.
Update collision_test example to use full playfield.

- A gap around the screen edges was introduced when the entity size was changed.
also unload atlas resources when calling `unloading()`
[#195] allows changing the imageLayer default origin point using the anchorPoint
[#195] fixed position calculation to match with "renderable within entity"  implementation

Default anchor point is however `(0,0)` to match with Tiled
implementation, while default anchor point for renderable is `(0.5,
0.5)`
[#167] use grunt for the build system

first pass update (time for lunch!) and currently broken.
(based on the grunt_config file initially provided by bsparks)
[#167] upgraded to grunt 0.4 and fixed the build system

Currently broken (todo) :
* jshint : generates too much error and is not part for now of the
default build option (source code need lots of fixes first)
* coffeescript : requires a new .coffeescript file (can anyone help?)
* banner: removed from now as format changed with grunt 0.4
* jsdoc; to be added (together with a new template for version 3.x)