A multitude of changes

- Fixed up filter check command
- Replaced remaining references to "soft disable" to "filter disabled"
- Fixed the final return statement in onCommand()
- Cleaned up code, especially relating to one line if/else statements
and return statements in onCommand()
- Replaced existing permissions check system based on the plugin.yml
with custom coded system that has a configurable flag in config.yml
- Miscellaneous comment/documentation changes