OLCTriangle: include finish point into search interval

The allowed points inside the closed trace is a closed interval
formed by [from, to], whereas a candidate set expects a
right-open interval of [from, to + 1).
OLCTriangle: relax shortest leg check a bit

The former 8/29 == 27.58% was a little bit too strict for some
border cases - this caused the algorithm to miss a better triangle
only if the origin of the flat projection was moved by some meters.
The new check 11/40 == 27.5% fixes that for the examined flights.
po: update French translation
po: update Swedish translation