Write marteladas using advices

[filipeom]

To fix #61 we would move these into advices such as:

__before(IsArrayIndex)__ function IsArrayIndexAdvice(P) {
  if (extern is_symbolic(P))
    return extern is_number(P)
}

Where the return in the IsArrayIndexAdvice is capable of hijacking the control flow and return something instead of running the IsArrayIndex function.

With this, we could move the esl symbolic marteladas into an advices.esl and place it in https://github.com/formalsec/explode-js to be linked with the compiled program js program