Classes will automatically inherit the virtual-ness of their base
class destructors. If the base class already has a virtual
destructor and the derived class needs default destructor semantics
then the derived class can omit defining the destructor in favor of
the compiler automatically defining it.
This has an additional benefit of reenabling move semantics. The
presence of a user-specified destructor automatically disables move
operations.
This commits also adds a script that does the amalgamation of headers
and .cpp files into the distributable version, removes the old
`generateSingleHeader` script, and also adds a very simple compilation
test for the amalgamated distribution.