This fixes a problem where libstdc++ incorrectly assumes that the allocator used with basic_string is DefaultConstructible. See: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56437
fix #575, fix #604, fix #608, fix #634, fix #712 All examples are rewritten: * Using Best Practices * Mostly self-contained * New examples to complete the feature matrix * The server-framework example is removed