Fix warnings by replacing deprecated bytestring functions with their replacements.
Add version constraints.
Updated tested-with in cabal file: GHC-7.8.2.
Clean up cabal file.
Use bytestring's toStrict and fromString methods introduced in 0.10.0.0.
Add support for lazy 'Text's, from Data.Text.Lazy.

This adds the 'ConvLazyText' class.

Also adds the following optional methods to the StringCells class:
  * unfoldrN64, defined by default in terms of unfoldrN, simply casting the
    'Int'.
  * altUnfoldrN64, defined by default in terms of unfoldrN, simply casting the
    'Int'.

This restricts StringCells by adding a constraint for 'ConvLazyText', requiring
an increment in the first two components to conform to cabal's versioning
policy, because this entails a major API change.
Bump version to 0.1.6.0 from 0.1.5.2.
Remove duplicate import of Data.Text.Lazy.IO, fixing warning.
Bump version to 0.1.6.1 from 0.1.6.0.