Switch to native code for copying and comparison.

--HG--
rename : Data/Text/Unsafe.hs => Data/Text/Unsafe/Base.hs

Oops, missed a file, and cabal didn't tell me\!

Clean up the cabal file and make sdist work.

Expose Builder.fromString.

Bump version

Test the lazy UTF-8 code.

Bump version

Merge

Make some of the low-level internals visible.

Necessary for people writing e.g. hash functions.

Make the developer flag control -auto-all.