Notebook Performance Improvements to Cell Editing/Output Changes/Execution Count Changes (#6867)

* edit perf

* Save multiline source in notebooks

* More merges

* Single, multi line works needs work

* Works with single + multi and recomputes active

* Actual perf improvements this time

* code cleanup

* Calculating output position on the fly

* Hmm can we use brackets to make this simpler?

* monday progress

* output working. lots of improvements.

* First tests working

* 10 tests now, fixed bugs

* Cleanup, add output test

* More fixes

* Need to still fix execution count bug

* Tests pass, added comments

* Cleanup

* PR comments round 1

* Deal with merge issues from master, layering

* Deleting duplicate file

* More PR Comments

* PR Comments

extensions/notebook/language-configuration.json

@@ -0,0 +1,19 @@
+{
+	"comments": {
+		"lineComment": "//",
+		"blockComment": [ "/*", "*/" ]
+	},
+	"brackets": [
+		["{", "}"],
+		["[", "]"]
+	],
+	"autoClosingPairs": [
+		{ "open": "{", "close": "}", "notIn": ["string"] },
+		{ "open": "[", "close": "]", "notIn": ["string"] },
+		{ "open": "(", "close": ")", "notIn": ["string"] },
+		{ "open": "'", "close": "'", "notIn": ["string"] },
+		{ "open": "/*", "close": "*/", "notIn": ["string"] },
+		{ "open": "\"", "close": "\"", "notIn": ["string", "comment"] },
+		{ "open": "`", "close": "`", "notIn": ["string", "comment"] }
+	]
+}