use 5.6 instead of requiring it; avoids accidentally compiling the stuff.

No obvious way to dodge the deprecated-our bug in 5.005; so, require 5.6 and be done with it.

Repair MANIFEST.

Add minimal tests.

Testing this thing will require forking a job to wait for the signal, signaling it, and watching for the output. Given the lack of fork on some systems this will not be trivial.

Initial version