Outdated echidna examples

[wildanvin]

Hello,

The echidna examples in the repo seem to be outdated. It says to run echidna-test instead of just echidna as in the documentation. I got an error when I tried echidna-test.

Also there are some minor corrections in the contracts:

• TestEchidna.sol:
  • To use assertions you need the flag --test-mode assertion instead of --check-asserts
  • echidna in not buggy anymore, so you don't need to switch to solc 0.7 to run assertions
• EchidnaTestTimeAndCaller.sol:
  • The third address is 0x30000 instead of 0x00a329C0648769a73afAC7F9381e08fb43DBEA70

I would be more than happy to create a PR with the corrections but I wanted to confirm with you first if you consider these changes valid.

Cheers.

[t4sk]

Please send a PR

[wildanvin]

Right away ser 🫡