Prevent unintended status updates

[vanita5]

• If a user has a typo in a command, the input is treated as a status update.
• Accidentally pasting text containing newlines into the CLI posts multiple status update.

TODO

• Inputs not recognized as a command by vorpal but starting with a / should trigger a prompt asking the user if they really want to post this and/or provide similar command suggestions
• Detect pasted text or limit status updating speed like TTYtter does