[Dillo-dev] form.cc: more refactoring

A set of small patches that clean up form.cc , mostly to do with DilloHtmlSelect . * refactor by creating new functions: - a_Html_parse_stash() - DilloHtmlSelect::ensureSelection() - DilloHtmlSelect::addOptionsTo() - DilloHtmlSelect::appendValuesTo() - DilloHtmlSelect::getCurrentOption() (cf. other getCurrent* methods) * make DilloHtmlSelect::options private * rename DilloHtmlInput::getInputValues() to appendValuesTo() (the new name is more mnemonic and consistent with the DilloHtmlSelect method above) Regards, Jeremy Henty