Changes for compatibility with ghc-7.10-rc2

2 modules: Name clashes caused by Applicative-Monad change in Prelude
2 modules: Ambiguities caused by Foldable/Traversable in Prelude
2 modules: Backwards incompatible changes in time-1.5 for defaultTimeLocale
9 modules: {-# LANGUAGE FlexibleContexts #-} (because GHC checks inferred types
           now, in addition to explicitly given type signatures)

Also silenced warnings about tab characters in source files.

gf.cabal

@@ -297,6 +297,9 @@ Library
   else
     build-tools: happy, alex>=3
 
+  if impl(ghc>=7.10)
+    ghc-options: -fno-warn-tabs
+
   if os(windows)
     build-depends: Win32
   else