use a mutable.HashMap instead of a mutable.Map
rewrite the .train method to create fewer objects

this uses a depth-size slider to directly create the pattern arrays,
and some index math to grab then target word.
change the default bot name to "artemisphd"
don't train on things we reply to

this way we don't end up with a bunch of strings like "artemisphd:" in
the logs
Merge branch 'perf.memory-usage'
Merge branch 'bugfix.bad-data'
Merge branch 'feature.bot-name'