added <s@script.step[<player>]> to get a script step of a player
Correct player.weather, fixes #713

- player.weather would explode on null rather than gently return null as
expected... and fail to return appropriately when it wasn't null too.
- readme link was old - updated.
Update the Player Leashes Entity event, fixes #712

- needed a cancel determine
- the event names had a typo
Make list.last work with empty lists

If last is used on an empty list, it would throw an exception - now just
returns null.
Fix YAML indexing, fixes #716

- trying to ++, or --, or whatever on an index item (EG my.key[1]) will
fail to increase it, as YAML tried to read the entire my.key as a basis
to increase, rather than the specific index.
Better startup debug output

- Fix formatting
- One extra try/catch to be super careful with registries
- a TODO
- absolute output on total failure (no citizens), regardless of debug
settings
- also slight adjustment to the tag script.step
Allow taking/giving money from/to offline players

- the offline inventory code throws errors... that code is beyond me, so
I've included a catcher / TODO about the error, and make give/take not
try to construct inventories when they aren't needed.
Add tag location.cuboids

A quick and simple tag to get a list of cuboids at a location
Catch up.