Chat fixes

Input fields now clear on reload of the web page.

Empty messages now can't be sent. Need to create some UI indicator of
the error, but for now the error is logged to the console at least.

UI Changes

The chat shortcode has been reworked. Rather than appearing as
paragraphs, the UI elements have been sorted into tabs that are hidden
by default and toggled by buttons.

IDs have been added+changed to accomodate this.

Button and input styling have been abstracted slightly. I am considering
moving these styles further out, to my blog CSS.

Adding live chat page