std: redesign to_string to always use operator <<

alib2abstraction/src/abstraction/ValueHolderInterface.hpp

alib2std/src/extensions/container/array.hpp

alib2std/src/extensions/container/bitset.hpp

alib2std/src/extensions/container/deque.hpp

alib2std/src/extensions/container/forward_list.hpp

alib2std/src/extensions/container/forward_tree.hpp

alib2std/src/extensions/container/linear_set.hpp

alib2std/src/extensions/container/list.hpp

...d/src/extensions/container/managed/managed_linear_set.hpp

alib2std/src/extensions/container/managed/managed_value.hpp

alib2std/src/extensions/container/map.hpp

alib2std/src/extensions/container/multimap.hpp

alib2std/src/extensions/container/multiset.hpp

alib2std/src/extensions/container/optional.hpp

alib2std/src/extensions/container/optional_ref.hpp

alib2std/src/extensions/container/pair.hpp

alib2std/src/extensions/container/ptr_array.hpp

alib2std/src/extensions/container/ptr_tuple.hpp

alib2std/src/extensions/container/ptr_value.hpp

alib2std/src/extensions/container/ptr_vector.hpp