Faster pages, and ImmediatelyFast

• Pages open faster: a fullscreen page now shows as soon as its picture has been sent, about one round trip after the command instead of two or three, and an overlay a round trip sooner. With 100 ms of lag a fullscreen page went from 0.5 s to 0.25 s, an overlay from 0.8 s to 0.4 s. A page a player has seen before only sends what changed.
• Fixed: players running the ImmediatelyFast client mod saw noise on map walls and nothing but a strip of noise in fullscreen pages and overlays. Everything now draws right with its default settings.
• Fixed: with Improved (Fabulous) graphics, water, glass, ice, particles and dropped items behind an overlay moved with the pointer while everything else stayed still. The world behind an overlay is now still throughout.
• Tip: network-compression-threshold=-1 in server.properties makes a player's first page open take several seconds longer on a slow connection. Leave it at the default (256).