Add a cabal flag to use the standard binary package

The standard binary package has improved efficiency and error handling [1], so
in the long run we should consider switching to it. At the moment, using it is
possible but not recommended, since it results in incomatible PGF files.

The modified modules from the binary package have been moved from
src/runtime/haskell to src/binary.

[1] http://lennartkolmodin.blogspot.se/2013/03/binary-07.html

gf.cabal

@@ -10,7 +10,7 @@ synopsis: Grammatical Framework
 description: GF, Grammatical Framework, is a programming language for multilingual grammar applications
 homepage: http://www.grammaticalframework.org/
 bug-reports: http://code.google.com/p/grammatical-framework/issues/list
-tested-with: GHC==7.4.2, GHC==7.6.2
+tested-with: GHC==7.4.2, GHC==7.6.3
 
 data-dir: src
 data-files: www/*.html
@@ -53,6 +53,10 @@ flag new-comp
   Description: Make -new-comp the default
   Default:     True
 
+flag custom-binary
+  Description: Use a customised version of the binary package
+  Default:     True
+
 library
   build-depends: base >= 4.2 && <5,
                  array,
@@ -63,6 +67,19 @@ library
                  pretty,
                  mtl
   hs-source-dirs: src/compiler src/runtime/haskell
+
+  if flag(custom-binary)
+    hs-source-dirs: src/binary
+    other-modules:
+      -- not really part of GF but I have changed the original binary library
+      -- and we have to keep the copy for now.
+      Data.Binary
+      Data.Binary.Put
+      Data.Binary.Get
+      Data.Binary.Builder
+  else
+    build-depends: binary
+
   extensions: 
   exposed-modules: 
     PGF
@@ -94,13 +111,6 @@ library
     GF.Data.ErrM
     GF.Data.Relation
     GF.Data.Operations
--- not really part of GF but I have changed the original binary library
--- and we have to keep the copy for now.
-    Data.Binary
-    Data.Binary.Put
-    Data.Binary.Get
-    Data.Binary.Builder
-    Data.Binary.IEEE754
 
 executable gf
   build-depends: base >= 4.2 && <5,
@@ -143,6 +153,13 @@ executable gf
   if impl(ghc>=7.0)
     ghc-options: -rtsopts
   hs-source-dirs: src/compiler src/runtime/haskell
+
+  if flag(custom-binary)
+    hs-source-dirs: src/binary
+    other-modules: Data.Binary.IEEE754
+  else
+    build-depends: binary, data-binary-ieee754
+
   extensions:
   main-is: GF.hs
   other-modules:
@@ -221,7 +238,6 @@ executable gf
     PGF.Binary
     PGF.Paraphrase
     PGF.TypeCheck
-    PGF.Binary
     PGF.Printer
     PGF.Optimize
     GFC