update changelog
be more permissive of output in debugger test
make backup longmess implementation more consistent with modern Carp
make stringification accessible outside magic subclass
trivial cleanups
disable debugging features unless required

perl's -d option will all of the debugging flags.  We don't use any of
the debug features though, so disable them.  This means we don't have to
provide a DB::DB sub.
rename color test env var
more strict check on debug flags
only override Carp::format_arg if it exists
add DEVEL_CONFESS_OPTIONS env var
colorize warns in evals
enable better names for evals and anon subs
clarify comment on debug flags
trivial cleanup
rename hacks to builtin