add local map loading

[Hybrid Dog]

local map saving is already possible
on servers local map loading would make the mapchunks become loaded from hard drive first and you would not need to wait for the server that it sends you the mapchunks

[rubenwardy]

this has been discussed before.

1. if this is caching, what if the map has changed?
2. if this is map generation, how to replicate the mods on the server?
3. these problems should be solved by improving the networking code

[Hybrid Dog]

this has been discussed before.

1. if this is caching, what if the map has changed?
2. if this is map generation, how to replicate the mods on the server?
3. these problems should be solved by improving the networking code

1. l thought about disallowing the player to walk into the chunk until it's loaded from the server.
2. The chunk only becomes preloaded if it's known (saved via local map saving).
3. If you have a bad connection or the server only sends near chunks and you use a high view range, you could see something there far away without waiting until it's loaded from server or without walking there.