At the initialization step, VREng downloads a configation file
of the initial World from an HTTP server.
Then all textures of this World are retrieved by HTTP
and kept in the memory cache of the VREng application.
So, the first World you encounter is the "Interconnection World" or
"Rendez-vous World" where you can find Gate boxes to go through (or teleport)
into other worlds. The Universe is not continue, worlds are discontinue.
All other World's configuration files and textures are downloaded
by the same way.
Worlds are kept in memory to allow back and forward operations of navigation.
It is also possible to come back to the original world with the home button.
Requests to this server are multi-threaded only for gif files
if your operating system supports POSIX multi-threading.
This pre-loading can take a certain time over the Internet,
but locally inside a site this operation take
1 to 5 seconds according to the network load and the amount of textures.
