use stderr for auth-client errors

Fixes regression (and failing self-tests) from before get-machine was merged
Default version for Todos app on mobile
Refactor console to separate out progress/status display
Rename Console.statusPollMaybe -> Console.nudge

We're working towards replacing patience
Delete dead function
Add yield to Console.nudge(), remove old exponential nudge which didn't look right
Move constants higher in console.js
Support spinner if progress fraction is unknown
Create repaint / depaint
Initialize _fraction
Advance spinner at constant speed
Remove dead code in progress
Add comment for commented out null-title check
Fix a large number of small mistakes
Move todo to the right place
Move patience to console
A few notes on what we need to do fully remove Patience
Replace the progress npm dependency with our own version

More or less copied code, for now (MIT licensed)
Don't bother with stop() function, just call depaint() directly
Cleanups from self-code review