Tokenstream

Feature
* Make it possible to know if a checkpoint was rolled back ([`0765e96`](https://github.com/vberlier/tokenstream/commit/0765e96aec93bcc6b0a60956ac509afd4f63e1c6))

Feature
* Add stream.reset() ([`1af0d47`](https://github.com/vberlier/tokenstream/commit/1af0d47b93082ae374ca8edef8f03f8a549e1fdb))

Fix
* Do not register the first alternative exception twice ([`1bb7102`](https://github.com/vberlier/tokenstream/commit/1bb71027bdf126ae5c439c149b34a99eeb5973fd))

Fix
* Make it possible to use None to disable previous rules ([`66e468a`](https://github.com/vberlier/tokenstream/commit/66e468ad068a3b1c9c34f0e72b63df38b7710a81))

Fix
* Add period to all error messages ([`c1c32b0`](https://github.com/vberlier/tokenstream/commit/c1c32b02732b66ac4080585f1360bfc429c7f0e2))

Fix
* Don't show token value if it's empty ([`6337bfd`](https://github.com/vberlier/tokenstream/commit/6337bfd35f0f51996cfae15174fe4f1b1428b7f2))

Fix
* Don't detect indent when the line is blank ([`175e02e`](https://github.com/vberlier/tokenstream/commit/175e02eadb75d027199f268edbede774632ab34c))
* Properly handle full dedent ([`04b9dab`](https://github.com/vberlier/tokenstream/commit/04b9dab09bf32cb368a60a009650689e7cf24145))
* Add eof and invalid tokens ([`264a398`](https://github.com/vberlier/tokenstream/commit/264a398ad4e55e89e0bfb503db2af98b38492d00))