Persist aliases in database

[Faek]

Aliases will be written and loaded from the database when the bot
starts, also added commands to list the aliases, and restore them if
they didn't load properly

[kabaka]

Thoughts:

1. It would be better to use the :done_loading event rather than :em_started so that aliases are set if the script is loaded later. This would mitigate most of the need for the restorealiases command (except for cases wherein another script has altered the aliases).
2. Should we then remove aliases on :unloaded? Seems like that would be wise.

Otherwise, this looks okay to me.