Finally deciding to move things into a proper license; which I can do
since I've never accepted (or had :( ) a pull request from another
person

This renames several interfaces that had names like IWhatever, since
that isn't a style that Java uses

IMap now returns optionals, instead of throwing an exception

IMap has some default methods that its various implementations were
overriding when they didn't need to

Pass to do some cleanups

The package root is now bjc, not io.github.bculkin2442.