Fix hotkeys (#1468)

* use hotkey using key instead of which (default)

* remove shift from block formatting hotkeys

* smartly exit formatting with backspace

* set markdown to off by default

* exit formatting with escape

src/app/state/settings.ts

@@ -28,7 +28,7 @@ export interface Settings {
 const defaultSettings: Settings = {
   themeIndex: 0,
   useSystemTheme: true,
-  isMarkdown: true,
+  isMarkdown: false,
   editorToolbar: false,
   useSystemEmoji: false,