In CreateReverseLookup(): Re-use the table we return.

In CreateReverseLookup(): Re-use the table we return.
In addon:ScanTrainerData(): Re-use teach and noteach tables.
In addon:ScanToolTip(): Remove confirmed_role, as it was never used. Now sets scan_data.found_class when a class string is found.
In addon:PrintScanResults(): Added flag descriptions for "Vendor" and "PvP". Replaced multiple class checks with a check for scan_data.found_class before checking flags. Re-worked logic and display behind extra class flag output for recipes which are not class-specific.