Initial libxml2 benchmark

Seems to be very slow right now, ~700 ops / sec. Will try to reuse the
xml reader next.
ignore libxml2 binary
Unify benchmark outut
Fix assert
Ok, libxml2 does 30k ops/sec without valgrind *g*
Reuse reader ptr, 30k -> 266k ops/sec!
Index samples from 1
Fix bug

My code for reusing the reader pointer was incorrect and so were the
benchmark results : /.
Make sure go benchmark is not cheating
Proper init
New node counting benchmark
Unify go and c benchmark
Use mb_per_sec as unit, gives a better perspective
Fix index
Expand nodes
Merge pull request #2 from johnsir/master

Create README.md
Merge pull request #1 from felixge/master

bench