Element procedures can now take arguments.
Add procedures that take arguments to the search page for testing.
Check whether an element responds to :present?, as collections of elements don't.
Allow elements to be evaluated under different parents.

The following option behaviour is now supported, where element1 and element2
are both gless elements: "element1.element2", which refers to element2
evaluated when element1 is considered the parent element.
Remove duplicate "Object level" header in documentation.
Support more types of parents.
In find_elem, tries += 1 was incorrectly placed, causing an infinite loop.
Add support for restricting element selection by children.
In test_github example, test :child selectors.
Check whether elements restricted by children are arrays, and avoid returning an element without non-watir selectors when it cannot be found with them.