array/Field.h: Clean Hashtable to Field conversion slightly

This is still rather hacky, and should probably be restructed or
pulled outside of the base Field class, which really shouldn't
know about Hashtable at all.
Merge branch 'windows'
Merge branch 'windows'
Work around compiler bug (affected Clang 3.1)
Merge branch 'master' of github.com:otherlab/core
array/Field.h: Clean Hashtable to Field conversion slightly

This is still rather hacky, and should probably be restructed or
pulled outside of the base Field class, which really shouldn't
know about Hashtable at all.
Merge branch 'master' into windows