XPath compiler support for id()
XPath compiler support for id()

This has been largely ported over from the Evaluator implementation.

ttasanen/oga,ttasanen/oga,ttasanen/oga,YorickPeterse/oga,ttasanen/oga,YorickPeterse/oga,YorickPeterse/oga,YorickPeterse/oga,YorickPeterse/oga,ttasanen/oga