Core / Core Module Split

I'd like to try and see if we can finish the work begun on cleaning the 
core of module stuff and arrive at a clean split between core and core 
modules in Jamaica.

Right now there are still in the core:

- a sprinkling of modvars
- a bunch of convenience functions (mainly xarUser and xarSecurity) that 
depend on calls to modules or modvars.

For the convenience functions I could see deprecating them and making 
them static methods of the Roles and Privileges classes.

This would incidentally already resolve a number of the modvar cases. 
Those remaining could be looked at one by one. Some might conceptually 
be considered important enough to become system vars.

Perhaps not the most important, but an immediate benefit to such an 
exercise would be to make rewriting the installer easier.

Any thoughts on this in general or other ideas on how to move the 
remaining module stuff out of the core?

Marc