Introduction of the class "std::unique_ptr"

[The class "unique_ptr"](http://en.cppreference.com/w/cpp/memory/unique_ptr "A smart pointer") which became officially available with the standard "ISO/IEC 14882:2011" can help to make the software a bit more robust for the case that [an exception will be eventually thrown](https://github.com/OHSystem/OHSystem/issues/207 "Changes for exception safety?"). It was introduced therefore into some source files.
* Some explicit calls of the delete operator and [unnecessary checks](https://github.com/OHSystem/ohsystem/issues/206 "Delete unnecessary null pointer checks?") can be removed because of its reuse.
* Specific build support can be activated by a corresponding parameter for the used C++ compiler.