Reexport PrimMonad from mutable vectors (#320)

* Reexport PrimMonad from mutable vectors

This allows to avoid extra import from primitive (and adding it to cabal file)
It's also in line with reexposrt of Storable and Prim type classes

Fixes #262

* Reexport RealWorld per @lehins suggestion

Also move reexports to bottom of module per @Bodigrim suggestion

Data/Vector/Generic/Mutable.hs

@@ -57,7 +57,9 @@ module Data.Vector.Generic.Mutable (
   fill, fillR,
   unsafeAccum, accum, unsafeUpdate, update, reverse,
   unstablePartition, unstablePartitionBundle, partitionBundle,
-  partitionWithBundle
+  partitionWithBundle,
+  -- * Reexports
+  PrimMonad(..), RealWorld
 ) where
 
 import           Data.Vector.Generic.Mutable.Base
@@ -71,7 +73,7 @@ import qualified Data.Vector.Fusion.Stream.Monadic as Stream
 import           Data.Vector.Fusion.Bundle.Size
 import           Data.Vector.Fusion.Util        ( delay_inline )
 
-import Control.Monad.Primitive ( PrimMonad, PrimState )
+import Control.Monad.Primitive ( PrimMonad(..), RealWorld )
 
 import Prelude hiding ( length, null, replicate, reverse, map, read,
                         take, drop, splitAt, init, tail )

Data/Vector/Mutable.hs

@@ -47,7 +47,10 @@ module Data.Vector.Mutable (
   nextPermutation,
 
   -- ** Filling and copying
-  set, copy, move, unsafeCopy, unsafeMove
+  set, copy, move, unsafeCopy, unsafeMove,
+
+  -- * Reexports
+  PrimMonad(..), RealWorld
 ) where
 
 import           Control.Monad (when)

Data/Vector/Primitive/Mutable.hs

@@ -50,7 +50,9 @@ module Data.Vector.Primitive.Mutable (
   set, copy, move, unsafeCopy, unsafeMove,
 
   -- * Unsafe conversions
-  unsafeCoerceMVector
+  unsafeCoerceMVector,
+  -- * Reexports
+  PrimMonad(..), RealWorld
 ) where
 
 import qualified Data.Vector.Generic.Mutable as G

Data/Vector/Storable/Mutable.hs

@@ -55,7 +55,9 @@ module Data.Vector.Storable.Mutable(
   -- * Raw pointers
   unsafeFromForeignPtr, unsafeFromForeignPtr0,
   unsafeToForeignPtr,   unsafeToForeignPtr0,
-  unsafeWith
+  unsafeWith,
+  -- * Reexports
+  PrimMonad(..), RealWorld,
 ) where
 
 import Control.DeepSeq ( NFData(rnf)

Data/Vector/Unboxed/Mutable.hs

@@ -51,7 +51,9 @@ module Data.Vector.Unboxed.Mutable (
   nextPermutation,
 
   -- ** Filling and copying
-  set, copy, move, unsafeCopy, unsafeMove
+  set, copy, move, unsafeCopy, unsafeMove,
+  -- * Reexports
+  PrimMonad(..), RealWorld,
 ) where
 
 import Data.Vector.Unboxed.Base