Many formatting fixes
Fit bib-items into 80 columns
Remove remaining from previous notebooks
Use notebook path, not hardcoded one

Also remove all output.
Drop using `listings` in favor of `algorithms`
Remove duplicate line
Add Clear button and don't store cache
Same applies to GPU notebook
Use Min instead of Mean for timings

We should fit to minimal time, since this is likely to be best benchmark not
disturbed by OS internals and other tasks.
References to GitHub and extended CPU discussion

Also adding few words in summary and reformatting everything to 80 columns.
It is Xeon Phi not Xeon [phi symbol]
Use hyperref for links which makes them all work
Minor formatting fixes