Change to use UncheckedIOException and un-checked exceptions

[alexec]

I know this is probably many changes, but it will make the code easier to use with Java streams.

I'm doing data analysis with this library, so I'm using streams extensively. You cannot throw checked exceptions in streams. What could be an elegant one liner becomes and ugly 5 line try-catch block.

[bitwiseman]

Duplicate of #1658. As I said there, I'm open to adding methods to support this as long as we do not make binary breaking changes.