Adds a function that creates a function that iterates an operator until
it either converges or exceeds a defined number of iterations.

Most of it is documentation changes.

The rest is more work on BlockReaders, as well as a simple command
language for configuring them.

SimpleBlockReader now properly gives line numbers

An isomorphism is a pair of functions between a source and destination
type. Ideally, they should be inverses, but java has no way to check
that by itself.