Elm-ts-interop-pro Demo and Setup Tutorial

[dillonkearns]

@choonkeat

'Elm' refers to a UMD global, but the current file is a module. Consider adding an import instead.ts(2686)

The output from elm make uses UMD, which means it supports both CommonJS or being added to the global namespace. TypeScript will give a warning about using UMD unless you set this in your tsconfig.json:

"allowUmdGlobalAccess": true

They give a little more detail in the docs for allowUmdGlobalAccess.