Large patch with lots of changes and fixes.
- Unified movement checking. Teleporting is now handled by
  entry/exit flags. Additionally, a region movement event is
  much closer to being added.
- Fixed an issue with enderpearls and exit/entry flags conflicting.
- Fixed a null check issue in several commands.
- Fixed allowed and blocked command flags making false matches and
  improved support for blocking/allowing specific command args.
Update CHANGELOG for 5.7.4 and 5.7.5
[maven-release-plugin] prepare release 5.7.5
[maven-release-plugin] prepare for next development iteration