Tokenstream

Fix
* Better mechanism for tracking alternative errors ([`4e0c3f2`](https://github.com/vberlier/tokenstream/commit/4e0c3f2e5a72e095c57a84ba5c59414151b06b19))

Fix
* Keep track of alternative errors ([`9bee458`](https://github.com/vberlier/tokenstream/commit/9bee458408166badad4795e8174935ea615ea055))

Fix
* Update docs ([`a788ff1`](https://github.com/vberlier/tokenstream/commit/a788ff194eb630555a01ba9837a160e40f97dbec))

Fix
* Sort expected patterns in explanation ([`c1c26cb`](https://github.com/vberlier/tokenstream/commit/c1c26cb874229a5e0319c882f3b6e5567fd14870))

Feature
* Make it possible to copy the stream ([`5a4a41c`](https://github.com/vberlier/tokenstream/commit/5a4a41c8f4a137a9c98bdda856cf4a4ba2169d0b))

Fix
* Get() method was returning a list instead of a single token ([`accf784`](https://github.com/vberlier/tokenstream/commit/accf7843f1263dbba6aa0893a157be608ed1758a))