Escape text chat in newChatMessage()
Sync chat history between peers
Not completly full proof, but seems to work reasonably well. If we do not have received chatHistory yet, ask for it each time a peer's video is added until we get it. Messages are escaped and formatting is preserved, including peer's color. One problem though: if you refresh the page, you will receive the history, but your own old message will appear on the left, as if it was another who send them. This is because there's no way to recognize it was you (previous session...)
Should fix #4