Pull in vuepress foir docs (as opposed to gitbook) (#742)

* Pull in latest @polkadot/dev, cleanup existing *.html

* Cleanups (old gitbook interfaces)

* Bump, WIP

* Ready for testing

* Update examples

* Include source

* Cleanup links

* Adjust links

* Add typedoc exclusions

* Default classes from class files

* Adjust imports

* Adjust config

* Re-add types split

* Update links to substrate interfaces

* Anchors for metadata

* Adjust links

* Restore HTML (to be deleted on CI)

* Bump deps

* Re-gen yarn.lock

* Remove a in links

* Adjust interfaces

.gitignore

@@ -1,5 +1,7 @@
+_book/
 build/
 coverage/
+docs/.vuepress/dist/
 node_modules/
 tmp/
 .DS_Store
@@ -13,5 +15,3 @@ npm-debug.log*
 yarn-debug.log*
 yarn-error.log*
 package-lock.json
-_book
-docs/html