Fixed some Checkstyle issues (after running "mvn checkstyle:checkstyle" and checking "target\checkstyle-result.xml")

Main:
- Removed unnecessary initialization for the logFileFlag field.
- Fixed some small Checkstyle issues (after running "mvn checkstyle:checkstyle" and checking "target\checkstyle-result.xml").

ReportUnit:
- Renamed the static getReportUnitComparator method to getComparator.

ViewerFrame:
- Changed a traditional for loop in the updateReportUnits method into a for each loop.

Constants:
- Fixed some small Checkstyle JavadocStyleCheck issues (after running "mvn checkstyle:checkstyle" and checking "target\checkstyle-result.xml").