packet-ppp.h/packet-rmt-common.h: Add #include <epan/params.h> (so certain other files need not do so).

Also: Add editor-modelines (packet-rmt-common.h)

Change-Id: Ib0c45285a9102bb21e8e3c216763ff8cc0150c32
Reviewed-on: https://code.wireshark.org/review/3611
Reviewed-by: Bill Meier <wmeier@newsguy.com>