Allow servers to contain multiple worlds

Although there are methods to have similar (i.e. using /transfer between server or a community-created proxy) behavior, there is currently no adequate way to have truly multiple worlds on one server. What I want is a server.properties option/separate download for a server that can have multiple worlds.

I believe that is should behave in a similar way to the below.

• In the place of the world folder, it is named "worlds."
• server.properties for the whole server shouldn't have world-related options.
• Command based per-world settings like view distance that are ordinarily in server.properties should be modifiable by commands and /reload.'
• A template folder for world templates.
• A /world command to manage worlds, delete/create worlds etc.

• This command should be able to create world from a template or with a certain set of features. (All modifiable settings associated with creating world in singleplayer should be available.)

• It should be possible to use both the properties of a world and the /world create command to set the macro arguments used in #load and #tick functions.

• Set who joins a world at the beginning.

• Improvements to the /transfer command to offer between world functionality with target selectors, etc.
• Universal data and resourcepacks, but also per-world ones.
• Template folder just for data and resourcepacks so that the /world create command can copy them into a world being created.