Remove full_name() function

Doesn't work for templates.

include/cppast/cpp_entity.hpp

@@ -162,11 +162,6 @@ namespace cppast
     /// \returns Whether or not the given entity is "friended",
     /// that is, its declaration exists as part of a [cppast::cpp_friend]() declaration.
     bool is_friended(const cpp_entity& e) noexcept;
-
-    /// \returns The full name of the [cppast::cpp_entity](), with all scopes.
-    /// \notes Enitites without a name ([cppast::cpp_using_declaration]() etc.) do not have a full name either.
-    /// \notes For (template) parameters the full name is the name itself.
-    std::string full_name(const cpp_entity& e);
 } // namespace cppast
 
 #endif // CPPAST_CPP_ENTITY_HPP_INCLUDED