templatekw: re-add showtags() to list tags keyword up in online help Changeset d69a7fc68ad5 removed "showtags()" definition for "tags" template keyword from "templatekw.py", because "namespaces" puts a helper function for it into template keyword map automatically. This works correctly from the point of view of templating functionality. But on the other hand, it removed "tags" template keyword from "hg help templates" unexpectedly, because online help text is built before "namespaces" puts a helper function for "tags" into template keyword map. This patch is a kind of backing d69a7fc68ad5 out, but this implements "showtags()" with newly introduced "shownames()" instead of originally used "showlist()".