New feature: Jupyter Books (#6095)

* Initial commit

* Fixed broken branch

* Show notebook titles in tree view

* Added  README

* sections showing in tree view

* Multiple books in treeview

* removed book extension, added to notebook

* removed book from extensions.ts

* addressed Chris' comments

* Addressed Charles' comments

* fixed spelling in readme

* added comment about same filenames

* adding vsix

* addressed Karl's comments

extensions/notebook/package.json

@@ -333,10 +333,20 @@
 					"connectionProviderIds": []
 				}
 			]
+		},
+		"views": {
+			"explorer": [
+				{
+					"id": "bookTreeView",
+					"name": "Books",
+					"when": "bookOpened && isDevelopment"
+				}
+			]
 		}
 	},
 	"dependencies": {
 		"@jupyterlab/services": "^3.2.1",
+		"@types/js-yaml": "^3.12.1",
 		"decompress": "^4.2.0",
 		"error-ex": "^1.3.1",
 		"figures": "^2.0.0",
@@ -364,4 +374,4 @@
 		"vscode": "1.1.5"
 	},
 	"enableProposedApi": true
-}
+}