Create plugin for wrapping the handlers from ghcide

The way PartialHandlers are chained in ghcide means earlier ones get masked by
ones added later in the chain.

Create GhcIde plugin so the underlying hover handler can be combined with other
configured hover handlers at the haskell-language-server combined handler.

Requires haskell/ghcide#490

Author: alanz

.gitmodules

@@ -10,5 +10,5 @@
 #     rm -rf path_to_submodule
 [submodule "ghcide"]
 	path = ghcide
-	url = https://github.com/digital-asset/ghcide.git
-	# url = https://github.com/alanz/ghcide.git
+	# url = https://github.com/digital-asset/ghcide.git
+	url = https://github.com/alanz/ghcide.git

exe/Main.hs

@@ -58,15 +58,20 @@ import System.Log.Logger as L
 import System.Time.Extra
 
 -- ---------------------------------------------------------------------
-
+-- ghcide partialhandlers
 import Development.IDE.Plugin.CodeAction  as CodeAction
 import Development.IDE.Plugin.Completions as Completions
+import Development.IDE.LSP.HoverDefinition as HoverDefinition
+
+ -- haskell-language-server plugins
 import Ide.Plugin.Example                 as Example
 import Ide.Plugin.Example2                as Example2
+import Ide.Plugin.GhcIde                  as GhcIde
 import Ide.Plugin.Floskell                as Floskell
 import Ide.Plugin.Ormolu                  as Ormolu
 import Ide.Plugin.Pragmas                 as Pragmas
 
+
 -- ---------------------------------------------------------------------
 
 -- | The plugins configured for use in this instance of the language
@@ -90,7 +95,8 @@ idePlugins pid includeExamples
       -- , hsimportDescriptor    "hsimport"
       -- , liquidDescriptor      "liquid"
       -- , packageDescriptor     "package"
-        Pragmas.descriptor  "pragmas"
+        GhcIde.descriptor  "ghc"
+      , Pragmas.descriptor  "pragmas"
       , Floskell.descriptor "floskell"
       -- , genericDescriptor     "generic"
       -- , ghcmodDescriptor      "ghcmod"
@@ -145,6 +151,7 @@ main = do
         -- (ps, commandIds) = idePlugins pid argsExamplePlugin
         (ps, commandIds) = idePlugins pid True
         plugins = Completions.plugin <> CodeAction.plugin <>
+                  Plugin mempty HoverDefinition.setHandlersDefinition <>
                   ps
         options = def { LSP.executeCommandCommands = Just commandIds
                       , LSP.completionTriggerCharacters = Just "."

ghcide

@@ -34,6 +34,7 @@ library
       Ide.Plugin.Config
       Ide.Plugin.Example
       Ide.Plugin.Example2
+      Ide.Plugin.GhcIde
       Ide.Plugin.Ormolu
       Ide.Plugin.Pragmas
       Ide.Plugin.Floskell

haskell-language-server.cabal

@@ -40,6 +40,7 @@ import           Ide.Plugin.Config
 import           Ide.Plugin.Formatter
 import           Ide.Types
 import qualified Language.Haskell.LSP.Core as LSP
+import qualified Language.Haskell.LSP.Messages as LSP
 import           Language.Haskell.LSP.Messages
 import           Language.Haskell.LSP.Types
 import qualified Language.Haskell.LSP.Types              as J