Add more listeners and functions

[spaceface777]

Right now the bot only has one listener (message). We should add more (quoted, mentioned ) to make it easier for the user to choose when to respond to a message.

We should also add more API functions since right now the only ones implemented are:

• loadmessages (used internally by the library to pass messages to the listener)
• sendmessage (quote used this but adds the quote to the message before sending it)
• getusername (used internally to get the bot's name from the token)

We should implement the rest of the API.

[spaceface777]

quoted and mentioned events added.