Split into smaller components + create snapshots on demand.

[recmo]

This PR is almost a complete rewrite, but I'll create a PR nonetheless, just to share what I've been doing.

• Split the behaviour of MiniMeToken into several components, each with their own contract.
• Add a createSnapshot() function to create snapshots on demand.
• Remove redundant entries from history table.

What needs to be done:

[ ] Turn into library so code can be shared between instances
[ ] Fix forking/cloning mechanism
[ ] Handle parent self-destruct
[ ] Fix tests
[ ] Add tests
[ ] Update documentation
[ ] Add documentation