Now we'll consider any message that doesn't start with a digit as a
continuation. This is _definitely_ in loose, best-effort territory now
since a continuation line could very well start with a digit, but
ultimately this is still better than the totally broken behavior that
preceded it.
Just to make sure that none of these heuristics interfere with producing
complete, accurate logs for TRACE, we'll skip the LevelFilter altogether
in that case.
In order to make this work reasonably we can't avoid using some funny
heuristics, which are somewhat reasonable to apply within the context of
Terraform itself but would not be good to add to the general "logutils".
Specifically, this is adding the additional heuristic that lines starting
with spaces are continuation lines and so should inherit the log level
of the most recent non-continuation line.
Martin Atkins