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

[Earl Miles]

Vladimir Zlatanov wrote:
>>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

Indeed, that is exactly why I suggest creating it as a completely separate 
engine. Though as I think on it, the current setup doesn't support running the 
same theme with multiple engines, that I'm aware of. I'm not actually sure.