[sotfware] `ImageMatching` Fix `convertAllMatchesToPairList` function
[sotfware] `ImageMatching` Fix `convertAllMatchesToPairList` function

* 'numMatches' bugfix: all matches for the first image were discarded when set to 0
* first image is now handled in the same loop as all others: first image ID in 'allMatches' map is the smallest one and will only have matches with larger IDs
poparteu/openMVG,poparteu/openMVG,poparteu/openMVG,poparteu/openMVG