CPP1114 — Make mapping of sequences more flexible

In 6.12 we define:

An unbounded sequence is mapped to a C++ std::vector.

For example a sequence of octets is now not optimal, in order for implementations to optimize sequences but users not to harm we propose to change this definition to

An unbounded sequence is mapped to a type delivering C++ std::vector semantics.

Flexible mapping for sequence and map types

Allow implementations more flexibility: in certain cases when the spec currently requires use of a C++ standard library type, the implementation should be able to use a substitute type that's interface-compatible.