Plausible large-scale example application

[andy-berry-dev]

see https://github.com/BladeRunnerJS/brjs-private/issues/1 for original issue

`And tutorial about how to create it.

Since it's big it'll probably be a tutorial in multiple parts.`

comment from @leggetter :
"I'd really like this to be something we all contribute to. So we use BRJS as well as build it."