Adding more information in the logging files

[Erwan Velu <erwan@enovance.com>]

Hi,

As you know, I've been working on having graphing tools into fio.
I'm running many benchmarks and organize the output by using genfio to 
name both files and logs.

But, there is always a but, it's impossible while taking a log file to 
understand in which setup fio ran to produce this log.

So I'd like to add several things inside the log file:
1- the role of each column
2- an header that reports what was fio setting for this log

Pro:
- Taking a log file is enough to understand the performance inside

Cons:
- That would break the current format : I'm thinking about commenting 
thoses lines.

Any ideas, comments ?

Cheers,