trying to follow nokogiri api
fix tags declaration
add c reference implementation
get find title example working, FFI::Pointer#get_pointer(offset) doesn't
work as expected, core dump start from offset 1,
read_array_of_pointer(size) works. maybe I misunderstood offset there.
add implementation of find title example
fix enumerable api of Vector
substitute hash access with method call in example
make example more rubish