Fix the make dist rule

In revision 459 I added a bug in the make dist rule in the sense that
the archive will include *all* of test/data directory, including the
.svn directory if it exists.

This patch fixes that problem and adds a distcheck hook that tests for
such errors in the future (files/directories matching the .svn and .git
patterns).

It also fixes a typo in the NEWS file.

Reviewed-by: imsnah