New enable/disable tool ready for testing

Henrik Stoerner wrote:

The host selection listbox lets you select multiple hosts. Just hold
down <ctrl> while you click on the hosts you want to disable.

Oh, I was referring to enabling them after they've already been disabled.  The ones in the "Currently disabled tests" block.  They have "enable" buttons next to each host, but no obvious way to do more than one at a time.

Tom