initctl: add optional TYPE argument to 'cond dump' command

Allow filtering of conditions in raw dump, i.e., the possibility to show
only conditions of a certain type.  The TYPE argument is not validated
in any way, so any prefix match is allowed, e.g.

   initctl cond dump service/s

Shows all conditions for services starting with 's'.

Fixes issue #272

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

man/initctl.8

@@ -145,8 +145,8 @@ Clear (deassert) user-defined condition,
 Show condition status, default
 .Cm cond
 command.
-.It Nm Ar cond dump
-Dump all conditions and their status
+.It Nm Ar cond dump Op Cm TYPE
+Dump all, or a given type of, conditions and their status
 .It Nm Ar ident Op Cm NAME
 Display indentities of all run/task/services, or only instances
 matching