Also, adapt the rest of lager to use this bitmask as well.

Helps with pattern matching.

I didn't want the lager_log_message record being used across application
boundaries, this will insulate other applications from any changes to
the message type's internal structure.

Various bugs uncovered during this testing were fixed and added to the
test suite.

Whenever we have the filename we ALWAYS have the module name, which is
effectively just as useful and already printed.

Tests now pass on both R15B and R14B03.

This is just silly busy-work since they're library applications, but
whatever.

Since the lager_format rewrite, ~p and ~w now have different behaviour
with regard to printing lists as strings.

Before this fix, the code assumed that processes without a registered
name omitted the {registered_name, X} tuple in the crash report. In
actual fact, process_info/2 returns [] when the process has no
registered name, so unregistered processes were being printed with a
"name" of "[]". This corrects the code to print the Pid in this case
instead.

The ~w formatting used before was not printing lists embedded in other
terms. This change uses trunc_io to print those terms safely and without
potentially introducing linebreaks (like ~p would)

az558

trunc_io:format checks the length after formatting funs/bignums etc
so it can go over.