opti bw area filter

[TitouanGragnic]

<!> this PR is not for dev

I can't compile on my computer so if you can compile for me, it can be very kind.

So for vesselle mask bw_areafilt is call with n equal to 1 so it's useless to get n labels max, so i remove this kernel and some other kernel,

for getting the biggest connected component i use cublas, this library does not work with uint so i change labels_sizes_d (uint) to (float) and with cublas we get the index of the max, this index is the label to keep, and i check if this label is upper 0, because -1 is not good and 0 is background.

please ask question if needed and check if it's compile and work,

moreover i will delete frontend useless setting later.

[Baschtien]

It in fact does not compile I'll see what i can do until you arrive