Rather than try to correct the issue of the Comparator crashing in
BookmarkManager because the Strings/HistoryItems were null, I modified
the HistoryItem object so that the title, url, and folder strings can no
longer be null but will instead be empty if set to null, this then
prevents the BookmarkManager from throwing an NPE when sorting the items
by title.
BookmarkManager stores bookmarks in a JSON database in the apps file
data directory. It includes helpful methods to export these bookmarks to
a backup file and import from that backup file. It also includes a way
to import bookmarks from the device's built in bookmark database.
