refactoring

- move over to env for unify et al
- fix issue where constraint had short context
- drop parameters block - make it clear where context is being used

src/Lib/Types.idr

@@ -341,7 +341,7 @@ Show MetaKind where
 
 -- constrain meta applied to val to be a val
 public export
-data MConstraint = MkMc FC Context (SnocList Val) Val
+data MConstraint = MkMc FC Env (SnocList Val) Val
 
 public export
 data MetaEntry = Unsolved FC Nat Context Val MetaKind (List MConstraint) | Solved FC Nat Val