Merge pull request #1 from Z7fritsch/master

A more elegent solution in Ruby ;-)
move into folder and add variations
add notebook
typo
slideshow
added more functional stuff
style
style
fix comment about range

... starts at zero, but does not really matter for our case
update slide layout
Merge remote-tracking branch 'origin/master'
ruby vs python

added benchmark stub.
fixed br0ken ruby implementation
common lisp implementation.