Store history in local storage

[moortens]

One of the nice things thats possible is to store the last x messages in localStorage.

This way the next time a user visits the webpage, the old conversation history could be shown. Paired with the chathistory spec it could give users a bit more of context.

Some questions arise from this though:

• What if the history data stored is old and obviously obsolete?
• Should the history be shown in different ways depending on where it comes from?
• How many messages should be stored by default, considering theres a 5MB limit on localStorage?