Privatize temporarily public (formerly implicit) class properties

[iansltx]

Resolution for this issue would include code that effectively reverts #747, switching class properties to private (or, if inherited and it makes sense to leave them that way, protected) that used to be implicity set (and thus public). In order for this to happen, each class instance will need to be audited to ensure that all public property accesses from outside that class go through getters, and all changes (if any) go through setters. Bonus points if this results in more test coverage and/or type declarations in affected code.