Don't waste time comparing ref files together

[ghost]

Although most people have no use for the Reference state in the Directories panel, it could serve as a nice speed optimization for long scans. Currently, dupeGuru stupidly wastes time comparing ref files together.

For word based searches, the time wasted is insignificant, but for content based ones, it could save IO operations by not reading md5 files of ref files matching.

More importantly, in dupeGuru PE, it would make a scenario where there's only a few picture to be checked against a large picture library much faster.

[ghost]

I have to add that one feature would be lost by doing this ticket, which is the fact that reference matches are shown in the result (in blue, uncheckable).

But compared to greatly enhanced speed for certain types of scans, I really don't see why I'd want to keep this feature.

[ghost]

(from [71e443ee2bd3]) [#77 state:fixed] Don't spend time comparing 2 ref files together.
http://bitbucket.org/hsoft/dupeguru/changeset/71e443ee2bd3/