when demangling c++ names, if resulting output is too long omit return type

[ilmanzo]

some demangled C++ names can get very verbose; if we demangle them with template parameters and so on, the risk is to see just the return type on the final report.

Let's get smarter and find out a compromise between completeness and usefulness in the html report; likely in case of very long symbols, the most interesting part to see is the class name and function name (and namespace if it fits).

for example, constructors and destructors can be abbreviated to just Class::Class and Class::~Class

[ilmanzo]

some examples:

std::_Rb_tree_iterator<std::pair<unsigned long const, unsigned long> > std::_Rb_tree<unsigned long, std::pair<unsigned long const, unsigned long>, std::_Select1st<std::pair<unsigned long const, unsigned long> >, std::less<unsigned long>, std::allocator<std::pair<unsigned long const, unsigned long> > >::_M_emplace_hint_unique<std::piecewise_construct_t const&, std::tuple<unsigned long const&>, std::tuple<> >(std::_Rb_tree_const_iterator<std::pair<unsigned long const, unsigned long> >, std::piecewise_construct_t const&, std::tuple<unsigned long const&>&&, std::tuple<>&&) [clone .constprop.0]

std::vector<int, std::allocator<int> >::_M_fill_insert(__gnu_cxx::__normal_iterator<int*,std::vector<int, std::allocator<int> > >, unsigned long, int const&)

std::vector<devpower*, std::allocator<devpower*> >::~vector()