Account all pointer types and remove unnecessary ones, modernize to c++17 where appropriate

[crackedmind]

[berkus]

Used types:

base/weak_unique_ptr.h base/flat_set.h base/flat_map.h base/tests/flat_map_tests.cpp base/type_traits.h base/optional.h base/ordered_set.h -- ? dialogs/dialogs_list.h dialogs/dialogs_indexed_list.h