102120: Extended the duplicates search list view. Now, the average
similarity of the found duplicates (excluding the original image) is shown as
table column. Sorting the result set by the average similarity is thus
possible. To implement this feature, the haariface had to be modified. It
returns a map of average similarities to a map of image ids to the set of
similar images instead of the map of image ids to the set of similar images.
Communicating the average similarity to the search list view was not possible
via slots and signals and this would have lead to sending a map of image ids
to average similarities and then distributing the appropriate average
similarity to the correct FindDuplicateAlbumItem. Instead, the average
similarity is communicated via the SearchXml-query as a field of the group.
This way, the correct item gets the correct similarity automatically. The
evaluation of the new field by an SQL query is surpressed by the introduction
of noEffect fields which need to have a prefix "noeffect_". So, the log is
not polluted by unnecessary debug information.

102121: The items in the FindDuplicatesAlbum were sorted by
lexicographic order which does not make sense for the average similarity
column (e.g. 100.00 is not correctly sorted). Thus, the less than operator
was adopted such that for the average similarity column, arithmetic order is
used. To make the code more stable against regressions due to reordering the
columns, an enum was introduced.

BUGS: 372217
FIXED-IN: 5.4.0
CCMAIL: frank@uni-potsdam.de