smarter removal of duplicate frames

Currently there is only an option to "remove every other frame" (fi_duplicates) and it's just a binary toggle.

(It's also not really clear whether this drops every other frame when it detects duplicates or just always does that -- SelectEvery(2,0) seems to suggest it's unconditional, but it's not really documented anywhere)
If it's currently unconditional, maybe something like TDecimate would be better

Often there are cases there are triple duplicated frames (new, duplicate, duplicate, new, duplicate, duplicate, etc) where you would want to discard both duplicates and interpolate additional frames
or more complex cases where the frame is partially duplicated, but not exactly so (and you might want to still discard every other frame).

Will there be support added for more complex options? (e.g. starting with detecting triple-duplicated frames, then partially duplicated cases)

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Also, I am interested in contributing to this project (these features in particular). The file "source_codes.txt" says that GPL source code can be found on the downloads page (http://www.svp-team.com/wiki/Download), but the download svpflow-4.3.0.168.zip only has the compiled shared objects (or dynamically linked libs) and some sample scripts. Is there somewhere else where I can find the source code?