Of course people still "can" distributed the sources under the
LGPLv3. However we provide COPYING.LESSER with additional grants.
Solution: specify these grants in the header of each source file.
* There is no clear reason why the map should hold const std::strings
* This class is never derived, there doesn't seem to be a compelling
reason to ever do so, so no need to make virtual members
* In general const member data is an anti-pattern, the *only* reason
is to prevent assignability, and the accepted idiom for that is to
to declare the assigment operator private. This change does so, and
also prevents copy construction.
