Make the ability to chat with your opponent more obvious

[trevorbayless]

Currently, chatting with your opponent online isn't an obvious feature at all. To do so, you need to type in the move input field prepend "send" to your message, like so:

I think either add it in the function bar for online games, or at a minimum document it in the new "notation" sheet (maybe rename to help)? Lots of options - this is just a placeholder issue to document it.

Additionally, when chatting change the text from "Move:" to "Chat:" (with a color change)?

[trevorbayless]

Partially completed as part of 59edef8