issues/286: get rid of Useless "no IPv4 address assigned" warning
Print some PPP CCP options; taken from issue #214, with changes.

Report the CCP protocol type as CCP.

Decode options for BSD, MRVCA, and DEFLATE compression.

Add some explanatory comments, and add some length checks, while we're
at it.
Use a common style for all option parsers.

Report "length bogus, should be ..." for invalid lengths for all
options.  That's not a fatal error - the next option can be parsed - so
don't return 0 in that case.

Don't put a colon after the option length unless there's something
following it.

Do the TCHECKs for particular CCP options in the code to handle the
option, as is done elsewhere.

Print the values for the CCP options on the same line, as is done
elsewhere.
ZMTP: fix an MSVC compiler warning

The prototype and implementation of 'zmtp1_print_datagram()' is slightly
different; the prototype has a 'const u_int len' as the last parameter.
Whereas the implementation has no 'const'. Hence I get a warning from
MSVC.