Add transport_opt() watchdog_config

To make the number of watchdogs sent before the transitions REOPEN ->
OKAY and OKAY -> SUSPECT configurable. Using anything other then the
default config is non-standard and should only be used for test.
Minor spec fix
Rework stats to avoid concurrent read and write

Counters read by diameter:service_info(SvcName, transport) can be
selected at the same time as the diameter_stats server is folding them
into another key, possibly resulting in inaccurate values. Have
diameter_stats select from the server process to avoid this and add
diameter_stats:sum/1 to sum values from all contributors on a given
term.
Rework watchdog suite to remove most timing dependencies

Count watchdog messages instead when this is an alternative.
Add testcases for watchdog_config
Tweak okay -> suspect config

Make it just a number of timeouts, without a new DWR being sent.
Distribution fixes

This is the functionality that allows transports to be shared between
identically-named services on different nodes, which has been neither
documented nor tested (until now).
Document distribution config
Add distribution suite
More flexible distribution config

Allow both share_peers and use_shared_peers to be a list of nodes, or a
function that returns a list of nodes.
Specify timeouts to ct_slave:start/2
Update appup
Deal with RFC 6733 change to Vendor-Specific-Application-Id

RFC 6733 has changed the arity of Vendor-Id in this Grouped AVP, from 1*
in RFC 3588 to 1 in RFC 6773. This impacts the generated dictionary
modules: Vendor-Id is expected to be list-valued in the 3588 dictionary,
integer-valued in the 6733 dictionary. This, in turn, breaks the
independence of capabilities configuration on a service or transport
from the dictionary that will be used to encode an outgoing CER or CEA.

This commit fixes this by massaging any Vendor-Specific-Application-Id
config as appropriate when constructing CER or CEA for a given
dictionary.
Update appup, vsn -> 1.4.1.1
Minor capx suite fix
Prepare release
Merge branch 'maint-r16' into maint
Minor tweaks and fixes

Fix a broken include in example code, remove an inappropriate ct:pal/2
outside of a testcase, echo more info from test/Makefile.
Add examples suite for testing example code

That is, code installed under examples/code in an installation.
Move example dict compilation to examples suite

From compiler suite.