Differences in length estimations from DGtal v1.0 to v1.1

[akrah]

I found some differences into DSS, FP and MLP from DGtal v1.0 to v1.1, still discussed in https://github.com/DGtal-team/DGtal/pull/1429.

The lenghtEstimators tool documentation proposes an example where there is the following differences between if using DGtal v1.0 (green curves) or v1.1 (purple).

I currently suppose this is relative to the introduction of deal with Circulators, but I didn't identify bug into the new code.

Steps to reproduce these differences:

1. Compile and include DGtal 1.0
2. Compile the DGtalTool lengthEstimators
3. Execute it: lengthEstimators -s flower -k 5 -R 20 -r 5 --steps 256 > lengths10.dat
4. Compile and include DGtal 1.1
5. Compile the DGtalTool lengthEstimators
6. Execute it: lengthEstimators -s flower -k 5 -R 20 -r 5 --steps 256 > lengths11.dat
7. Generate figures using gnuplot and this length.txt file:

$ gnuplot -c length.txt length11.dat length10.dat