Homogenise verovio JS dependency

[musicog]

We should use the Verovio supplied by the npm verovio-dev package

[alastair]

I had a quick look at doing this, except if you load it using an import statement, it might go through your build system (it made my node run out of memory and crash). Especially when using create-react-app this doesn't give us the ability to use webpack configuration to exclude it. Perhaps there's a different way that might give us the same benefit...?