Add + to toggle full screen

Architype.js

@@ -292,6 +292,12 @@ class Architype {
         e.stopPropagation();
         e.preventDefault();
         return;
+
+      case '+':
+        this.toggleFullScreen();
+        e.stopPropagation();
+        e.preventDefault();
+        return;
     }
 
     let elem = document.activeElement;
@@ -339,6 +345,14 @@ class Architype {
     this.renderGeneration_ = this.serialized_.generation;
     render.postMessage(this.serialized_);
   }
+
+  toggleFullScreen() {
+    if (document.fullscreenElement) {
+      document.exitFullscreen();
+    } else {
+      this.container_.requestFullscreen();
+    }
+  }
 }
 
 <!--# include file="Editor.js" -->

README.md

@@ -82,6 +82,7 @@ considered a reasonable tradeoff.
 * `m` Select the next theme (light/dark)
 * `M` Select the previous theme (light/dark)
 * `?` Add a help section below the current line
+* `+` Toggle fullscreen
 
 Note that it is possible to delete the help section with the normal delete
 command `d`.