Design the degree to which mazu should handle versioning and provenance information

[theJasonFan]

This is a lib and not a CLI, and can support basic known instantiations of index types. e.g. pufferfish + piscem. ModIndex should report / store only basic information, and have the info be split corresponding to k2u and u2pos data structures. CLIs that use mazu and need fine grain control over metadata should use the newtype idiom i.e. type MyIndex(ModIndex<...>) and handle metadata / provenance info as appropriate for MyIndex.

[theJasonFan]

We'll build a CLI / mapper with mazu to drive specs and design requirements.