Added a serialize_long utility function.
Added a serialize_long utility function.

Encodes a python int as a 8 bytes integer. Maybe serialize is not really
the right word, but...

ilveroluca/pydoop,kikkomep/pydoop,mdrio/pydoop,elzaggo/pydoop,crs4/pydoop,kikkomep/pydoop,ilveroluca/pydoop,elzaggo/pydoop,simleo/pydoop,mdrio/pydoop,mdrio/pydoop,simleo/pydoop,kikkomep/pydoop,ilveroluca/pydoop,mdrio/pydoop,elzaggo/pydoop,ilveroluca/pydoop,ilveroluca/pydoop,elzaggo/pydoop,simleo/pydoop,kikkomep/pydoop,simleo/pydoop,crs4/pydoop,mdrio/pydoop,crs4/pydoop,simleo/pydoop,crs4/pydoop,crs4/pydoop,kikkomep/pydoop,elzaggo/pydoop