Use scientific >= 0.3.1

scientific-0.3.1 exports the Text and ByteString Scientific Builders from
the following modules respectively:

- Data.Text.Lazy.Builder.Scientific
- Data.ByteString.Builder.Scientific

--HG--
extra : rebase_source : ba52e4d4efebc4d8b28a83f100ede322c2cc85dd
extra : histedit_source : 24672de0b23f74e2ddf9b17f054444fa542bed17
Use floor on Scientifics again

scientific-0.3 provides a DoS safe floor.

--HG--
extra : rebase_source : 01c184cd9999662e8a73b5819d498fae979c3723
extra : histedit_source : 810ed4934aa7f76f0fe7b63449609ceeba89025b
Use Scientific.fromRealFloat and Scientific.toRealFloat

--HG--
extra : rebase_source : e4f41aa4600e3623a6a0ac72b29fe644f49c5f52
extra : histedit_source : 18d65f0d3fa236b43343cb25349d6778384dd2f4
Renamed fromRealFloat back to fromFloatDigits

I think the latter is more descriptive.

--HG--
extra : rebase_source : ccbcb71c7b8901da4d510f586c02ec5e9c411143
extra : histedit_source : 6db4361fc35e24c7649d96316cd3d4f9170e3a6b
Use Scientific.toRealFloat instead of realToFrac in scientificToNumber

--HG--
extra : rebase_source : f50acab7fd39d3e6ef22aeb91394b8bb73c238bb
extra : histedit_source : 504f28b4100ae2197e85c19fc1b14cab1ea72a51
Add warning about space-usage on the Fixed instance

--HG--
extra : rebase_source : 625058aecd476ec8f0140965e04787974ad21b70
extra : histedit_source : 13c9b34b80a918675cffa1311881b00b9e3511d5