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

Nobody has claimed this yet.

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

Start at the HTML report's C++ demangling path and inspect how long symbols are currently rendered. Done means very long names prioritize the class and function, retain a namespace when it fits, and abbreviate constructors or destructors as Class::Class or Class::~Class.

Written by the indexing model from the issue text.