clearing byte array early in 'Loader' code path
added missing 'static' declaration
Avoiding array creation side-effects in performance critical areas

On iOS (AOT compiler), Array/Vector.push and  Math.min/max cause the creation of temporary arrays.
more places where 'push' should be avoided
new helper method for AGAL texture lookup flags
first version of DisplacementMapFilter

Beware: doesn't yet work with atlas textures for the displacement map.
avoiding more allocation side-effects