CmdNews: Version methods should generate all items, regardless of priority

Drop the flag about full/abbreviated report being passed to the version
methods. The methods shold just generate the NewsItem objects, the
CmdNews::execute will take care of displaying only the ones matching the
verbosity level the user selected.

src/commands/CmdNews.cpp

@@ -108,7 +108,7 @@ void NewsItem::render () {
 // - The .by attribute modifier
 // - Exporting a report
 // - Multi-day holidays
-void CmdNews::version2_6_0 (bool full, std::vector<NewsItem>& items) {
+void CmdNews::version2_6_0 (std::vector<NewsItem>& items) {
   NewsItem writeable_context (
     true,
     "'Writeable' context",