By using binary comprehensions. Add string-valued addresses to codec
suite.

To accept any nested list of codepoints and binaries. A list containing
a binary was previously misinterpreted and the documentation was
incomplete.

Also, rework codec suite slightly to be able to specify values for which
decode o encode is the identity map, for which encode should succeed,
and for which encode should fail.

Commit f0a36c79 broke the handling of such configuration, resulting in a
function clause error in diameter_capx if the list was not of length 3,
and faulty extraction of application id's otherwise.  Only record-valued
config was properly interpreted.

* anders/diameter/release/R16B01/OTP-11120:
  vsn -> 1.4.2
  Update appup for R16B01
  Trailing whitespace and copyright fixes
  Minor macro simplification
  Move app/appsrc from src/base into src

* anders/diameter/request_spawn/OTP-11060:
  Make spawn options for request processes configurable

That is, for the process that's spawned for each incoming Diameter
request message.

Option 'accept' allows remote addresses to be configured as tuples or
regular expressions. The remote addresses for any incoming (aka
accepted) connection/association are matched against the configured
values, any non-matching address causing the connection/association to
be aborted.

RFC 6733 says that certain 5xxx result codes must be accompanied by
Failed-AVP, and decode populates #diameter_packet.errors with
Result-Code/AVP pairs for errors it detects. However, Failed-AVP was not
set in the outgoing answer if the handle_request callback returned
{answer_message, 5xxx}. It is now set with the AVP from the first pair
with the specified Result-Code, if found.

Note that {answer_message, 5xxx} doesn't handle all cases in which a
5xxx answer is required, only that in which the setting above is
appropriate. If it isn't then handle_request should construct its answer
and return {reply, Ans}.