Sonar Major Warnings: Visibility Modifier

- scope of fields have been reduced to private or default from protected
- getters & setters created where needed
- dummy values assigned to ```S_ENTITY_LT``` & ```S_ENTITY_GT```, as they were missing in the last commit - needs to be corrected to appropriate values - @chriswhocodes - what should they be set to?
- Sonar has flagged a number of other fields that should stay protected as subclasses make use of them, can be considered as false positives at this instance