Switch internal representation to UTF-8

README.markdown

cbits/cbits.c

cbits/utils.c

src/Data/Text.hs

src/Data/Text/Array.hs

src/Data/Text/Encoding.hs

src/Data/Text/Foreign.hs

src/Data/Text/Internal.hs

src/Data/Text/Internal/Builder.hs

src/Data/Text/Internal/Encoding/Fusion.hs

src/Data/Text/Internal/Encoding/Utf8.hs

src/Data/Text/Internal/Fusion.hs

src/Data/Text/Internal/Fusion/Common.hs

src/Data/Text/Internal/Fusion/Size.hs

src/Data/Text/Internal/Fusion/Types.hs

src/Data/Text/Internal/Lazy/Encoding/Fusion.hs

src/Data/Text/Internal/Lazy/Fusion.hs

src/Data/Text/Internal/Lazy/Search.hs

src/Data/Text/Internal/Search.hs

src/Data/Text/Internal/Unsafe/Char.hs