Modify the block placement limit to allow for the odd random packet or two

When the connection between a minecraft client and a server
(e.g. me and the spigot test server) is bad sometimes two placement
packets will arrive at the same time. When the extra one gets canceled
any blocks placed against it get rejected by the server causing the
whole chain to disappear. This fixes this by allowing more packets
to occur whilst making the window wider (since the client seems to be
capped at about one placement every 100ms on a normal connection)