Optional VS Obligatory tests & necessary utils

New optional vs obligatory test classes & methods have been implemented: each attribute of simple "attribute(..)"-pattern is tested whether it behaves in line with agreed optional / obligatory attribute behaviour.
I.e.: an optional attribute must return either a vector, entity or boost::optional _and_ have a none_t-deleter overload - an obligatory attribute must _not_ return boost::optional and must _not_ have a none_t-deleter overload.
A brief summary is shown for all attributes - if an attribute is neither optional nor obligatory the test fails and the summary expands with details.
Not yet tested attributes are all those of more complex "getAttribute", "deleteAttribute", ... patterns - they require far simpler tests.