Added optimization to just read the first N bytes

It's not done using stream yet. Next version will.
Consistent camelCase notation

Sorry for the mix, in my code it's: camelCase for methods and lower case
with underscores for vars, so to easily differentiate them.
Hopefully fixed indentation problems.

The problem comes from the presence of tabs in the original file.
I would gladly do a whitespace-cleanup with Emacs if you agree :-)

Really tabs are a pain when sharing code.
While not every project agree on 4 or 2 spaces, most of them agree on
preferring spaces indentation:
https://google-styleguide.googlecode.com/svn/trunk/javascriptguide.xml
http://javascript.crockford.com/code.html
http://www.python.org/dev/peps/pep-0008/#tabs-or-spaces
Move readFirstBytes method as requested

I fully agree that the previous function order was not logical. But
I found more logical to have "public" (i.e. "exported") variables
first (because they are what the developers are looking for at first
glance), and then put below the "private" and last "tree-leaf" functions
and variables. The longer one reads into the file, the deeper in the
dependency chain variables one finds.
Merge pull request #24 from madarche/improve-examples

Added optimization to just read the first N bytes