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

[Vladimir Zlatanov]

> 1) Including lots of templates might be a performance drain; I've already done 
> some experiments that show that even with an opcache, more PHP files with small 
> amounts of code is significantly slower to process than 1 PHP file with lots of 
> code. Though I think this could be rectified with a PHPTemplateCompiled engine,
> where the compiler extracts all of the files necessary and puts them into a 
> single template file. This would have an advantage of making design easier by 
> separating the templates, but impacting the performance much less...but it does 
> have the disadvantage of the compiling process being a disconnect between 
> modifying and using. Still, I think there could be some value here.
+++ as long as it is an optional feature, in some hosting environments you don't 
have write access to fs