Changed 'Anisotropic Filtering' to a MULTIX option

I also added the options No, 2x, 4x, and 8x. Previously enabling Anisotropic Filtering only set the value at 1, which made no visual difference.

http://i4.minus.com/iZo8yMivaiMkT.png No
http://i3.minus.com/ibxS6Zi79XkWnT.png 2x
http://i7.minus.com/ibsUYCaCeCYSG9.png 4x
http://i2.minus.com/iUKxAhXl6FolG.png 8x