migrate to new @types/vscode, add vsce devDependency

The vscode library is deprecated in favor of @types/vscode.
See https://code.visualstudio.com/api/working-with-extensions/testing-extension#migrating-from-vscode

This also add vsce as a devDependency, so you don't need to install
it globally. Instead you can run it via npm run vscepackage. This
simplifies the README (or future "hacking" instructions when the
extension is published)

README.md

@@ -61,9 +61,8 @@ Install the VS code extension (see https://code.visualstudio.com/docs/setup/mac
 
 1. `cd extension/`
 2. `npm ci`
-3. `npm install vsce --global` (may require `sudo`)
-4. `vsce package`
-5. `code --install-extension ghcide-0.0.1.vsix`
+3. `npm run vscepackage`
+4. `code --install-extension ghcide-0.0.1.vsix`
 
 Now openning a `.hs` file should work with `ghcide`.
 

extension/package.json

@@ -49,8 +49,8 @@
 		"vscode:prepublish": "npm run compile",
 		"compile": "tsc -p ./",
 		"watch": "tsc -watch -p ./",
-		"postinstall": "node ./node_modules/vscode/bin/install",
-		"test": "npm run compile && node ./node_modules/vscode/bin/test"
+		"test": "npm run compile && node ./node_modules/vscode/bin/test",
+		"vscepackage": "vsce package"
 	},
     "extensionDependencies": [
         "justusadam.language-haskell"
@@ -59,10 +59,11 @@
 		"vscode-languageclient": "^4.1.4"
 	},
 	"devDependencies": {
-		"typescript": "^3.3.1",
-		"vscode": "^1.1.28",
-		"tslint": "^5.12.1",
+		"@types/mocha": "^2.2.42",
 		"@types/node": "^10.12.21",
-		"@types/mocha": "^2.2.42"
+		"@types/vscode": "1.35.0",
+		"tslint": "^5.12.1",
+		"typescript": "^3.3.1",
+		"vsce": "^1.66.0"
 	}
 }