[Dillo-dev] form.cc: select and option classes

Two patches here. The first patch turns DilloHtmlSelect and DilloHtmlOption into classes and implements their constructors and destructors. It also makes DilloHtmlInput::DilloHtmlInput() responsible for creating the select object if necessary (as determined by examining the input type) and removes the select argumentfrom DilloHtmlInput::DilloHtmlInput() and DilloHtmlForm::addInput() . The second patch is a small followup that simplifies select handling elsewhere: instead of checking the input type we check if the input's select is non-NULL. Regards, Jeremy Henty