Compiler: Warn when an operation is called not at the top level

[josephjclark]

This is an antipattern we see all the time, where an operation is nested and must be called like post(...)(state):

get('/some-data', (state) => {
   post('some-data, state.data)(state)
})

The compiler should be able to detect nested operation calls like this and log some kind of warning to users. It may even be able to suggest a refactor snippet to show what we mean.

[josephjclark]

Difficulty right now is that Lightning won't see it. Need to fix #392 first