typo.
add .gitignore
change NeedReseed to return a reseed policy type.
export reseed policy.
import entropy qualified as SE
fix a typo
add a SystemRandom which pull random bytes directly from the system, without
putting any pseudo step in the middle.

The security of this depends on the underlaying implementation which is system dependant.

The windows implementation uses CryptoGenRandom and is probably safe to use as such.
The unix implementation uses /dev/urandom which is unix dependant.
clarify the outputing policy, and remove limits on generation.

allow to generate more data than the cprg limits using inefficient
concat or list appending. it's still unwise to generate a huge amount
of data.
swap rng parameter to be last.

It has been suggested that it allow easier wrapping in the state monad.
bump version