No tests for unicode handling in Elm names

[emmabastas]

Elm names (i.e. variable, type, module, variant and port names) can contain unicode lower-/uppercase characters, but elm-format does not test for this in it's test suite.

What is lower and uppercase is determined by haskells Data.Char.isLower and Data.Char.isUpper (source: conversation with Evan)

[lydell]

I dug into this unicode stuff not too long ago. Here are some interesting links and regexes for this in case it is of interest:

https://github.com/rtfeldman/node-test-runner/blob/15deef63cc69f9968076353fa6af9c28d41fc1aa/lib/Parser.js#L229-L235