Reformat comments broken by previous commits
action 'id' field is now a string

This makes it clear to a user manually editing his JSon file that
it can be an arbitrary string.
rename checkJsonVersion to upgradeJsonVersion

It does not really check anything, but does the actual change to upgrade
the file.
Add "delayAfter" field to most actions, defaulting to 200ms

When using "afterPrevious" trigger, a smooth animation should make a
short pause between two mouse movements. Do this by default, and make it
easy to override.
check duration for null-ness explicitly

We don't want '"duration": 0' (explicitely say zero) to be equivalent to
no duration (let the default apply).