* Moved action=history to use an Action subclass

* Moved action=history to use an Action subclass
* Removed obsolete aliases PageHistory and PageHistoryPager; unused
* Maintained backward compatibility with HistoryPage; extensions using it will still work
* Use local context instead of global variables
* Removed calls to OutputPage::setPageTitleActionText() and OutputPage::setSyndicated(), the first one does nothing and the second one is overriden by the setFeedAppendQuery() call just below
* Call Linker methods statically
* Fixed bug where feedEmpty() was not called on empty history since casting a ResultWrapper object to boolean always returns true even when there's no row