Possible bug in CrossSearch

[adworacz]

https://github.com/pinterf/mvtools/blob/d8bdff7e02c15a28dcc6e9ef2ebeaa9d16cc1f56/Sources/PlaneOfBlocks.cpp#L1583-L1584

This might be a very old bug.

Shouldn't this code be using a - j and a + j, similar to the - i and + i right above it? It would make sense, to search both directions of a cross, instead of the same direction twice.

I think this bug can be found in both this mvtools, but also both Vapoursynth plugins as well.

Looking at the same code in x264 would suggest that the search should be done in both directions: https://github.com/mirror/x264/blob/master/encoder/me.c#L171-L174