Added for_each function in type_traits to ease the iteration over various containers.
Added for_each function in type_traits to ease the iteration over various containers.

Improved some type_traits functions/classes (array_data_type, nested_data_type)

Signed-off-by: Étienne Schmitt <25d5031dc1a1d443222aec9a4e916501ae23c255@inria.fr>

untereiner/CGoGN_2,etienneschmitt/CGoGN_2,cgogn/CGoGN_2,david-cazier/CGoGN_2,cgogn/CGoGN_2,untereiner/CGoGN_2,david-cazier/CGoGN_2