Change the shebang line from /bin/sh to /bin/ksh in all base rc.d
daemon scripts.

discussed with and OK aja@
OK tb

Fix base rc.d scripts after the recent rc.subr change.

ok halex@

wire up the bits for tftp-proxy, which is called tftpproxy from rc.d's
point of view.

mostly ok sthen@ ajacoutot@, who were discussing the feng shui of the
start_daemons chunk