Eliminate mutual dependencies between the GF compiler and the PGF library

+ References to modules under src/compiler have been eliminated from the PGF
  library (under src/runtime/haskell). Only two functions had to be moved (from
  GF.Data.Utilities to PGF.Utilities) to make this possible, other apparent
  dependencies turned out to be vacuous.

+ In gf.cabal, the GF executable no longer directly depends on the PGF library
  source directory, but only on the exposed library modules. This means that
  there is less duplication in gf.cabal and that the 30 modules in the
  PGF library will no longer be compiled twice while building GF.

  To make this possible, additional PGF library modules have been exposed, even
  though they should probably be considered for internal use only. They could
  be collected in a PGF.Internal module, or marked as "unstable", to make
  this explicit.

+ Also, by using the -fwarn-unused-imports flag, ~220 redundant imports were
  found and removed, reducing the total number of imports by ~15%.

src/compiler/GF/Grammar/Analyse.hs

@@ -10,7 +10,7 @@ module GF.Grammar.Analyse (
 
 import GF.Grammar.Grammar
 import GF.Infra.Ident
-import GF.Infra.Option ---
+--import GF.Infra.Option ---
 import GF.Grammar.Macros
 import GF.Grammar.Lookup
 
@@ -18,7 +18,7 @@ import GF.Data.Operations
 
 import qualified Data.Map as Map
 import Data.List (nub)
-import Debug.Trace
+--import Debug.Trace
 
 stripSourceGrammar :: SourceGrammar -> SourceGrammar
 stripSourceGrammar sgr = mGrammar [(i, m{jments = Map.map stripInfo (jments m)}) | (i,m) <- modules sgr]

src/compiler/GF/Grammar/Binary.hs

@@ -12,9 +12,9 @@ module GF.Grammar.Binary(decodeModule,decodeModuleHeader,encodeModule) where
 import Prelude hiding (catch)
 import Control.Exception(catch,ErrorCall(..),throwIO)
 
-import Data.Char
+--import Data.Char
 import Data.Binary
-import Control.Monad
+--import Control.Monad
 import qualified Data.Map as Map
 import qualified Data.ByteString.Char8 as BS
 
@@ -23,7 +23,7 @@ import GF.Infra.Ident
 import GF.Infra.Option
 import GF.Grammar.Grammar
 
-import PGF.Binary
+import PGF() -- Binary instances
 
 -- Please change this every time when the GFO format is changed
 gfoVersion = "GF02"
@@ -346,3 +346,5 @@ decodeFile' fpath = addFPath fpath (decodeFile fpath)
 addFPath fpath m = m `catch` handle
   where
     handle (ErrorCall msg) = throwIO (ErrorCall (fpath++": "++msg))
+
+decodingError = fail "This file was compiled with different version of GF"

src/compiler/GF/Grammar/CF.hs

@@ -25,7 +25,7 @@ import GF.Data.Utilities (nub')
 
 import Data.Char
 import Data.List
-import System.FilePath
+--import System.FilePath
 
 getCF :: FilePath -> String -> Err SourceGrammar
 getCF fpath = fmap (cf2gf fpath) . pCF

src/compiler/GF/Grammar/EBNF.hs

@@ -24,7 +24,7 @@ import GF.Grammar.Grammar
 
 import Data.Char
 import Data.List
-import System.FilePath
+--import System.FilePath
 
 
 

src/compiler/GF/Grammar/Grammar.hs

@@ -68,15 +68,15 @@ import GF.Data.Operations
 
 import PGF.Data (FId, FunId, SeqId, LIndex, Sequence, BindType(..))
 
-import Data.List
+--import Data.List
 import Data.Array.IArray
 import Data.Array.Unboxed
 import qualified Data.Map as Map
-import qualified Data.Set as Set
-import qualified Data.IntMap as IntMap
+--import qualified Data.Set as Set
+--import qualified Data.IntMap as IntMap
 import Text.PrettyPrint
-import System.FilePath
-import Control.Monad.Identity
+--import System.FilePath
+--import Control.Monad.Identity
 
 
 

src/compiler/GF/Grammar/Lexer.hs

@@ -1,5 +1,5 @@
 {-# LANGUAGE CPP,MagicHash,BangPatterns #-}
-{-# LINE 3 "lexer/Lexer.x" #-}
+-- {-# LINE 3 "lexer/Lexer.x" #-}
 
 module GF.Grammar.Lexer
          ( Token(..), Posn(..)
@@ -8,7 +8,7 @@ module GF.Grammar.Lexer
          ) where
 
 import GF.Infra.Ident
-import GF.Data.Operations
+--import GF.Data.Operations
 import qualified Data.ByteString.Char8 as BS
 import qualified Data.Map as Map
 

src/compiler/GF/Grammar/Lookup.hs

@@ -40,8 +40,8 @@ import GF.Grammar.Predef
 import GF.Grammar.Lockfield
 
 import Data.List (sortBy)
-import Data.Maybe (maybe)
-import Control.Monad
+--import Data.Maybe (maybe)
+--import Control.Monad
 import Text.PrettyPrint
 import qualified Data.Map as Map
 

src/compiler/GF/Grammar/Macros.hs

@@ -22,14 +22,14 @@ import GF.Data.Operations
 import GF.Data.Str
 import GF.Infra.Ident
 import GF.Grammar.Grammar
-import GF.Grammar.Values
+--import GF.Grammar.Values
 import GF.Grammar.Predef
 import GF.Grammar.Printer
 
 import Control.Monad.Identity(Identity(..))
 import qualified Data.Traversable as T(mapM)
 import Control.Monad (liftM, liftM2, liftM3)
-import Data.Char (isDigit)
+--import Data.Char (isDigit)
 import Data.List (sortBy,nub)
 import Text.PrettyPrint
 

src/compiler/GF/Grammar/PatternMatch.hs

@@ -24,10 +24,10 @@ import GF.Infra.Ident
 import GF.Grammar.Macros
 import GF.Grammar.Printer
 
-import Data.List
+--import Data.List
 import Control.Monad
 import Text.PrettyPrint
-import Debug.Trace
+--import Debug.Trace
 
 matchPattern :: [(Patt,rhs)] -> Term -> Err (rhs, Substitution)
 matchPattern pts term = 

src/compiler/GF/Grammar/Printer.hs

@@ -29,15 +29,15 @@ import GF.Infra.Option
 import GF.Grammar.Values
 import GF.Grammar.Grammar
 
-import PGF.Expr (ppMeta)
+import PGF.Data (ppMeta)
 import PGF.Printer (ppFId, ppFunId, ppSeqId, ppSeq)
 
 import Text.PrettyPrint
-import Data.Maybe (maybe, isNothing)
+import Data.Maybe (isNothing)
 import Data.List  (intersperse)
 import qualified Data.Map as Map
-import qualified Data.IntMap as IntMap
-import qualified Data.Set as Set
+--import qualified Data.IntMap as IntMap
+--import qualified Data.Set as Set
 import qualified Data.Array.IArray as Array
 
 data TermPrintQual 

src/compiler/GF/Grammar/Values.hs

@@ -24,7 +24,7 @@ module GF.Grammar.Values (-- * values used in TC type checking
 --Z tree2exp, loc2treeFocus
 	      ) where
 
-import GF.Data.Operations
+--import GF.Data.Operations
 ---Z import GF.Data.Zipper
 
 import GF.Infra.Ident