[PR] Upgrade hash algo to use password_hash/password_verify

[Script47]

Just in case it gets seen here first before Github: https://github.com/ChristopherDay/Gangster-Legends-V2/pull/54

Added a backward compatible way to update the hash algo from `sha256` to use the preferred `password_hash`/`password_verify` methods.

- Introduced two new methods `hash_password($var)` and `verify_password($salt, $password, $compareTo = null)` and deprecated the old `encode` method
- Removed the user ID salt as `password_hash` handles salt generation

I've tested login and register with both passwords using the old algo and the new one but can't test forgot password locally, though, theoretically it should work as login and register do.

Edited October 3, 2020 by Script47