Performance improvement for artifact sorting.

Conflicts:

	Core/src/org/sleuthkit/autopsy/report/ReportGenerator.java
Moved methods only used by ArtifactData into the ArtifactData class. Cache rowData for each ArtifactData.

Conflicts:

	Core/src/org/sleuthkit/autopsy/report/ReportGenerator.java
Removed stopwatch and debug printlns.

Conflicts:

	Core/src/org/sleuthkit/autopsy/report/ReportGenerator.java
Finish merge cleanup
Merge pull request #396 from rcordovano/report_fix_merge

Report performance improvements merge from master