v1.0

Introduces a breaking change regarding v0.9 because of the introduction of start_time and end_time. Data migration script provided (see README's Data Migration section for details).

v0.9

Marking current master as v0.9, as soon there will be a v1.0 with a small breaking change (I'm switching to optional start_time+end_time for tasks, from the current due_time), so better to tag and start using semver to mark breaking changes (those will always be major version bumps).