* [examples] Update some READMEs.
These contained some copied-and-pasted text that had not been updated.
Also added a note about the need to switch private key for the second command
in `simple_token`.
* [examples] Update input file for lottery.
* [examples] Remove `leo build` from `vote` script.
* Add tests for ChaCha::rand*
* Add Chacha::rand* to AST, tyc, and codegen
* Add lottery example
* Regen expectations
* Add check asserting that command is only used in finalize block
* Update example and related CI