Merge pull request #592 from mcmonkey4eva/master

More PRs for the good of bugfixity
Merge pull request #593 from mcmonkey4eva/master

Yay entities
Don't assume arg != null.
Updates/additions to modifyblock command.
Add to: argument to ShowFake to show block changes to multiple players.
Add iconcrack_[id] for PlayEffect

This allows users to use
- playeffect <player.location> iconcrack_268
to display an item break effect for any block or item.
Fix YAML command bug

- yaml write:KeyName id:MyId
currently throws an NPE, so you have to do
- yaml write:KeyName value: id:MyId
to make a blank key. This commit allows the former.

This also fixes a problem with PlayEffect from the previous commit
Merge pull request #594 from mcmonkey4eva/master

PR for the fixing of previous fixes
Merge pull request #595 from Morphan1/master

Fixes and fixes for fixes
Add player.has_finished[script_name] and player.has_failed[script_name] tags.
Fix meta.
Fix location.yaw.simple, fixes #600

1.7 changed the yaw calculations it seems
also fix a meta typo
also make location.identifySimple return notables. Though that function
isn't even used yet.