conf: settle the block format's key names and value shapes

The initial implementation was done using a naive translator of the
legacy one-liner format key by key, so it inherited encodings that the
block format exists to remove: a timeout packed into a script path, a
small comma-and-colon language inside the log string, sigils standing in
for booleans, and a log key (services) carrying three (!) types.

Settled naming against systemd, OpenRC, FreeBSD rc.subr, s6 and SMF.
Match systemd's semantics, not its naming.

    pid          -> pidfile, plus pidfile-create for the rare case
                    where Finit writes the file rather than the daemon
    environment  -> envfile, since it names a file to source, and the
                    top-level environment {} block sets variables
    pre/post/... -> exec-start-pre, exec-start-ready, exec-stop,
                    exec-stop-post, exec-reload, exec-cleanup, each
                    with its own -timeout instead of "SEC,script"
    halt, kill   -> stop-signal, stop-timeout
    restart      -> restart for the policy, restart-max for the count
    log          -> a block with file, priority and identity, where
                    /dev/null and /dev/console are spelled as paths
    group        -> group and extra-groups, no longer positional
    nowarn       -> a leading - on command, as on envfile

List-valued keys take plural names.  Aliases are desc, cond, mod,
caps, env, halt and kill; an alias may abbreviate the canonical name
or preserve a legacy spelling, nothing else.

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

test/conf-template.sh

@@ -25,7 +25,7 @@ test_teardown()
 say 'Install a block-format template'
 run "echo 'service serv:%i {'                          >  $FINIT_RCSD/available/serv@.conf"
 run "echo '    description = \"Template for %i\"'      >> $FINIT_RCSD/available/serv@.conf"
-run "echo '    pid         = \"/run/serv-%i.pid\"'     >> $FINIT_RCSD/available/serv@.conf"
+run "echo '    pidfile     = \"/run/serv-%i.pid\"'     >> $FINIT_RCSD/available/serv@.conf"
 run "echo '    command     = \"serv -n -p -P /run/serv-%i.pid\"' >> $FINIT_RCSD/available/serv@.conf"
 run "echo '}'                                          >> $FINIT_RCSD/available/serv@.conf"