Better accuracy of dropped frames for HTTP drains

This patch moves the counting of lost messages outside of the drain
buffer and brings it into the HTTP drain itself, which will treat
them as a new message part of its queue, to be produced once the queue
is empty and no errors happened while sending other messages.

This frame will contain the accumulated errors for all previous frames
(lost while parsing, and lost while trying to send and failing after too
many retries or malformed requests).

The patch also removes bits of dead code here and there, and adds tests,
which add a dependency for meck. The dependency will never be part of
the standard compile path, and so a new test config has been created: it
mirrors the regular config, but allows specific dependencies not to be
included in production.

The new way to build tests has been documented.
Adding test using framing funs for HTTP drain

verifies the formatting of messages with a bit more depth, although it
still doesn't try to parse them on the receiving end.
live update code for v62
Fixing framing for L10 messages
Fixing live update to account for nonempty queues
Simplifying CT suite running

- Won't fail to report info on a failure
- Will allow custom test run with logplex.spec
- doc is updated
Reloading module that was missing and may crash
Merge branch 'v62'