Deriving Data and Typeable in various data structures.
Merge remote-tracking branch 'upstream/master'
Merge branch 'master' of github.com:ucsd-progsys/liquid-fixpoint into ucsd-progsys-master

Conflicts:
	src/Language/Fixpoint/Types.hs
Exposing SymConst, SubC, and WfC

- Also added some operations on environments.
Nanojs adds symconsts to literals.

- They should not be added in fixpoint, cause we need to unify all sorts to int first
Merge pull request #21 from panagosg7/symconst

Symconst: adding symconsts to the list of literals. Required to properly support string constants.