Uncompress function in paintchat.php
Various small fixes in script.js and also a new compressEvents function
for uploads to backend (pack two shorts into an int and BASE36 it to
save space)
Change single canvas to play and draw canvases

Use two canvases instead of one so people can draw without interruption
while the other canvas renders drawings from other people.
backend process_post rewrite, frontend LoadDataInterval to constant
Make frontend also send event time and let backend store it
Remote communication fully working.
Save button working.