license / docs pass:

- add new docs for loading, exploring, sharing, embedding, and offline usage
- add license file / license banner

electron app:
- for now, don't bundle docs, open in native browser

embeds:
- support 'embed' option, 'replayonly' or 'full' (default if no url)

ui:
- display package.json version in info menu

package.json:
- update scripts to match README
- move electron entrypoint into extraMetadata
- add scripts for packaging as module

README: minor edits

_sass/custom/custom.scss

@@ -35,3 +35,13 @@ $nav-width-md: $nav-width;
 .rwp-blue {
   color: $rwp-blue;
 }
+
+.pad {
+  padding: 0.5rem;
+}
+
+.cap-header {
+  padding: 0 0 0 10px;
+  margin: 0;
+}
+