Add LINKTYPE_BLUETOOTH_LE_LL/DLT_BLUETOOTH_LE_LL.

Also fix a formatting error.
Get rid of the RTAC serial linktype for now.

Some discussions are still occurring on it; we'll add it back when we
finish.
Put LINKTYPE_RTAC_SERIAL in.
Merge branch 'master' of git+ssh://bpf.tcpdump.org/tcpdump/master/git/htdocs

This merge is necessary because Git appears to think it's necessary.  I
guess I forgot to do a "git pull" just before my push.
LINKTYPE_BLUETOOTH_LE_LL doesn't include the preamble.