Milestone hatching commands

This milestone includes new commands:

hopla hatch {eggname} {potionname}
hopla hatch-all

Further improvements:

• --today and --tomorrow flags for hopla add todo.
• hopla feed-all now supports feeding previously released pets
• code improvements (e.g. higher test coverage, better naming)

Previous improvements:

• hopla cast for spells that don't require a target uuid