Removal of small connected componants in level-set mode (ß test int 2D with the -rmc option)

Level-set users can ß-test a new option in mmg2d: the -rmc option.
This option allows to remove small spurious componants during the level-set discretization.

To test this new feature, pull the develop branch of the Mmg repository!

Do not hesitate to give us your feedback here.