Add documentation of the future methods
Some minor fixes around error_code_future_released, moved makeFutureNil into transaction.go since it's not used elsewhere
Add copyright/license text
New approach to safety: rather than trying to detect any and all nil pointer dereferences, inappropriately constructed objects, etc., we now protect ourselves through opaque, lightweight structures containing indirected pointers to our actual data. Our public types are now safely copyable, etc., and if you construct your own outside of our API you'll likely get a nil pointer dereference panic.

--HG--
rename : fdb/example_test.go => fdb/transactor_test.go
Options are now exposed like Snapshot, by function that returns a *Options object.
Use reflect package for dynamic method dispatch of atomic ops in the stacktester
C.GoBytes is definitely a better call than C.memcpy
RangeResult methods without pointer receiver