Added:
- AMRecursiveDirectoryCompare enum DirectoryCompareResult now has value
NotYetRun=11

Altered:
- AMDirectorySynchronizerDialog now sets lastCompareResult to NotYetRun
on construction (for consistency)
- AMDirectorySynchronizer now uses its lastCompareResult in order to
determine whether or not it has already checked the directories. This
ensures that the process of checking the directories is not run twice.