* Renaming Xml::reasonDropDown to Xml::listDropDown to make sure it doesn't imply...

* Renaming Xml::reasonDropDown to Xml::listDropDown to make sure it doesn't imply a special usage.
* Adding support for custom name and id, custom class, and custom tabindex to Xml::listDropDown
* Changing the order of parameters Xml::listDropDown accepts.
* Updating ipblock, file deletion and page deletion forms so they all use this new Xml element rather than holding three copies of similar code.
* Removing variables which are no more used in the three above forms.
* Renaming a few variables to follow the coding style of MediaWiki.