[NeoStats-Devel] NeoStats core list access restrictions

Tonights addition of core side map generation represents the final stage in
restricting access to core lists for things like users, servers, channels
etc to the core and only the core. As such the lists are static to each sub
system and the temporary GetxxHash functions used during development of this
have been removed. Please do not change this even to provide access to
another core subsystem. 

Each core list now has a list walk function so that code wishing to access
information from the lists merely provide a handler and are passed each
entry in turn. This means that list access is always performed in a known
safe manner in the core so any updates to such areas only need one area of
code updating. Where possible, the core also uses this same system for
accessing it's own lists for the same reason of maintainance and to test the
versatility of the API. The API allows a module to pass a pointer of it's
choice to the system which will be passed on to any callback which should
give us a great deal of future proofing.

Core subsystems other than the list owner should use the list walker. The
system should be much simpler to use since you merely write the part that is
normally within a list/hash walk loop and that is your handler. 

There are still a few areas that could be improved in the core but this will
be an ongoing investigation and any major change to the API would be
postponed to 3.1.

Mark.