Add a login system that allows users to regain control of a character after logging out

[wsowens]

Currently, players have no means of "logging in" to an account. We need a system that looks like this:

Welcome to MuddySwamp?
Do you have an existing character? (yes/no) yes
Great! Enter the password for that character:
**********
You have loaded your character, Bill the Wizard.

Or:

Welcome to MuddySwamp?
Do you have an existing character? (yes/no) n
Creating a character...
You are a Healer.
Enter a password to recover this account later:
*********
What is your name?
Matt
Welcome, Matt the Healer!