remove unused editpage title

The title was set to editpage, but then always changed.
And some code tested for this. Remove this dead code.

IkiWiki/CGI.pm

@@ -281,7 +281,6 @@ sub cgi_editpage ($$) { #{{{
 	eval q{use CGI::FormBuilder};
 	error($@) if $@;
 	my $form = CGI::FormBuilder->new(
-		title => "editpage",
 		fields => \@fields,
 		charset => "utf-8",
 		method => 'POST',

IkiWiki/Plugin/editdiff.pm

@@ -48,8 +48,7 @@ sub formbuilder_setup { #{{{
 	my $form=$params{form};
 	my $page=$form->field("page");
 
-	return if $form->title ne "editpage"
-	          || $form->field("do") ne "edit";
+	return if $form->field("do") ne "edit";
 
 	$page = IkiWiki::titlepage(IkiWiki::possibly_foolish_untaint($page));
 	return unless exists $pagesources{$page};