Disambiguate Common Options, clarify text

Disambiguate the initial description of Common Options; the options with go in either $options or $attributes array, depending on the chosen method;
Eliminate '$options' from the name of each option entry in the description to avoid confusion;
Reformat element/option names or values with code tags to follow general style of the page and improve readability;
Rephrase/clarify some unclear wording up to Creating Input Elements section.