[development] Move all core modules into their own directories.

[Kobus Myburgh]

> I don't use anything but PHPTemplate, but I think that we want to keep

> the engine system. Why don't we just leave the theme_ function
inclusion 
> mechanism to the engine? PHPTemplate will require separate files, and

> other engines can do what they please.

PHPTemplate is simple enough to use, and I think is sufficient.
Anything simpler will add overhead and the question should be - how much
overhead is allowable for a certain amount of simplicity?

I am all for throwing the rest out and sticking with PHPTemplate. I
don't know of many software programs or utilities that has more than one
engine. I can't talk about Linux, as I know next to nothing thereabout,
but Windows, for example, has one 'theme engine' if you can call it
that, and you can just add different themes? I think one engine is
sufficient.

Kobus