Add operator overloading to the CSM script

[rehno-lindeque]

Operator overloading is needed for using/manipulating parameters (see also issue #24)...

For example one might have

var a = range([0,0,0], [10,15,0.8]);
var b = range(2, 4);

box({dimensions: b * a})

where b * a is actually a relatively complicated operation that will probably be translated to some overloaded operator such as mul(b,a).

Nevermind this, one might even want operations like sqrt(b) and cross(a,r)...