Syntax changes and renames to State and Flow Handlers

[calebjclark]

All of these except the last are ones we discussed yesterday. I implemented them in Hero to see if it made my scripts feel simpler and they did, so I submitted a PR.

1. The allTrue in State has been simplified down to just all with the first argument being assert and not { assert }:

hero.waitForState({
  all(assert) {
    ....
  }
});

2. The State Methods (checkState, waitForState, and registerFlowHandler) now accept a simplified first argument of just the all(assert) callback:

hero.waitForState(assert => {
  ....
});

3. checkFlowHandlers has been renamed to triggerFlowHandlers to be more precise in what it does.

4. checkState has been renamed to validateState. I understand why we went with "checkState" as "ensureState" wasn't quite accurate (it doesn't actually ensure anything, it just returns a boolean). However, check never felt right in my script flow; I want it for a purpose, to validate the current state. Anyway, I'm cool reverting back to "checkState" if you want.

One thought... We've discussed wanting to pass state assertion results into Flow Handler callbacks. Similarly, returning a "validation object" from validateState of what assertions passed would be really nice and further lean towards the validateState name.