add copied_files metric to copy tasks.

This commit also adjusts a number of things in saga.Task to allow for arbitrary metrics to be added.  Those changes need to be reflected in *all* @SYNC calls which are supposed to be used in async tasks -- they now get an additional parameter "_from_task", which, you guess it, contains the task object itself, so that metrics etc. can be registered and updated.
more work on copy with relative paths
Revert "implemented file / directory .close()"

This reverts commit 83b4470fc94a179cccfc2daf16042493dcf12132.

Revert the additional close() methods, as those are already available via the
namespace.entry class -- with a colliding method signature

Please open tickets if close() still fails on any package/adaptor which
inherits from namespace.
more fixes toward the file copy and staging tickets
merge
fix backward compatible arg parsing and error reporting in tests