Support on-the-fly learning

[Sean Kauffman]

The mining algorithm currently relies on a pre-loaded trace to determine the alphabet prior to learning. It should, in principle, be possible to modify the algorithm to support streaming a trace. The matrix would need to be expanded dynamically as the alphabet grows, but this isn’t so hard. The other problem is figuring out when to stop, but doing what we do right now with stdin seems fine (just waiting for EOF). Nothing necessarily wrong with supporting the pre-loading of traces, but it is unfortunate that this is how it must be done for the mining algorithm.