-Wno-tabs not supported by older GHC
New IsString instances
Allows for convenience construction of attribute Content and text nodes.
Declare language extensions in source file
Instead of using cabal flags. Also, even DataTypeable can be optional
if not compiling with GHC.
Update maintainer information
Add ghc-prim to build-depends when building with GHC 7.2 and 7.4,
because GHC.Generics was moved to base in 7.6.
Bump version to 0.3.6.
Add instances of Generic for GHC >= 7.2.
Bump version to 0.3.5.
Add NFData instances to types.
Update source repository locations.
Add derived 'Data' instances to types.
Use DeriveDataTypeable. Bump version to 0.3.2.
Add ``Ord`` instances for all types.