No distinct types when using bounded types with the C++11 mapping

[jwillemsen]

The IDL to C++11 mapping states:

• A bounded string type is mapped to a distinct type to differentiate from an unbounded string.
• A bounded wide string type is mapped to a distinct type to differentiate from an unbounded wide string.
• A bounded sequence is mapped to a distinct type to differentiate from an unbounded sequence.

This is currently not done by OpenDDS when enabling the IDL to C++11 mapping

[mitza-oci]

Added to documentation for 3.15 and leaving this open.