cxx: prettier name demangling

Alternative to !156 (closed)

Uses the approach mentioned in !156 (comment 1006442): we first try to demangle ourselves for the most common STL types. As a fallback we use cxxabi.

Required for !281 (merged)

TODO:

• Test if this actually works
• Add std::map demangling
• Reworking remaining exceptions using std::type_info
• Add unit tests for the explicitly implemented types