mididump(1): Initial revision

A new utility which dumps MIDI 1.0 events in real-time.

Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Reviewed by: dev_submerge.ch
Differential Revision: https://reviews.freebsd.org/D46418

(cherry picked from commit f57efe95cc25ae527c632d4ffcf064799f922216)
(cherry picked from commit b8007cfdb72c1be27d1d93937886fd60f21915ab)
(cherry picked from commit feb9ba2993cf6aefa49b7b17ca49c52210c26035)
(cherry picked from commit 53314e34d5e8e7f781ab990805b22f7a56bc0580)