In the absence of other info, try to find the last die() or warn().
Stop using File::Slurp (the other methods already used Genome::Sys).
Use File::ReadBackwards in our new die/warn method.
Don't slurp the entire output file into memory.
Stop slurping the file in remaining case.

Rework helper functions to assume they get one line at a time.
Merge pull request #306 from tmooney/find_die_messages

Determine Errors: try to find the last die() or warn().