Add Codec#{upcast,downcast} for safe casting
Add examples of mapped enums with reserved values
Add Err subtype for case where an unknown discriminator is encountered when decoding
Add toString methods to various codecs
CHANGELOG update
Bump to scala 2.11.4
Setting version to 1.6.0
Setting version to 1.6.1-SNAPSHOT
Bump version
Merge branch 'master' into topic/shapeless-2.1

Conflicts:
        src/main/scala/scodec/codecs/CoproductCodec.scala