Import xy model

XY model - modified chess-board algorithm
(http://www.ibiblio.org/e-notes/webcl/mc/xy2.html)
Ported XY model to Webkit implementation

    * Changes to work in webkit implementation
    * Deleted cl_gl.js - using file in commons
    * constants for numbers
    * function to initialize spins images
    * Avoid unnecessary instances of typed arrays
    * Some improve in code style

    Reviewed by: Afonso Costa.