A file reading benchmark

[Martin Nowak]

> On my machine (Mac OSX Lion), the Python code clocks around 1.2 seconds  
> and the D code at a whopping 9.3 seconds. I looked around where the  
> problem lies and sure enough the issue was with a slow loop in the  
> generic I/O implementation of readln. The commit  
> https://github.com/D-Programming-Language/phobos/commit/94b21d38d16e075d7c44b53015eb1113854424d0  
> brings the speed of the test to 2.1 seconds. We could and should reduce  
> that further with taking buffering in our own hands, but for now this is  
> a good low-hanging fruit to pick.
>
Nice, I just got shocked yesterday by seeing that we call fgetc for every  
char,
those are usually macros and as we already maintain the per system  
*_unlocked
functions we might probably use the macro expansions.