C++ Libraries – Best Practices for Distributing Libraries

You are correct that anything STL - actually, anything from any third party library which is templated - is best avoided in any public C++ API. You also want to follow the long list of rules at http://www.ros.org/reps/rep-0009.html#definition to inhibit ABI breakage which makes programming public C++ APIs a chore.

And the answer regarding C++11 is no, this standard isn't touching that. More interesting is why not? The answer is because C++17 is very much touching that, and for C++ Modules to be implemented we need exported templates to work, and for that we need a LLVM type compiler such as clang which can dump the full AST to disc and then do caller-dependent lookups to handle the many ODR violating cases in any large C++ project - which, by the way, includes lots of GCC and ELF code.

Lastly, I see a lot of MSVC hate and pro-GCC comments. These are very misinformed - GCC on ELF is fundamentally, and irretrievably, incapable of producing valid and correct C++ code. The reasons for this are many and legion, but I'll quickly quote one case example: GCC on ELF cannot safely produce Python extensions written using Boost.Python where more than one extension based on Boost.Python is loaded into Python. That's because ELF with its global C symbol table is simply incapable by design of preventing ODR violations causing segfaults, whereas PE and MachO and indeed the proposed C++ Modules specification all use per-module symbol tables - which incidentally also means vastly faster process init times. And there are plenty more problems: see a StackOverflow I answered recently at https://stackoverflow.com/questions/14268736/symbol-visibility-exceptions-runtime-error/14364055#14364055 for example where C++ exception throws are irretrievably fundamentally broken on ELF.

Last point: regarding interoping different STLs, this is a big pain for many large corporate users trying to mix third party libraries which are tightly integrated to some STL implementation. The only solution is a new mechanism for C++ to handle STL interop, and while they're at it you might as well fix compiler interop too so you can (for example) mix MSVC, GCC and clang compiled object files and it all just works. I'd watch the C++17 effort and see what turns up there in the next few years - I'd be surprised if nothing does.

does it make sense to incorporate all libraries into my project e.g. in _3rd_party_libs_ folder ?

Do whatever you want, but keep it consistent. I do note that you've listed examples such as boost/sqlite; these should be standard in your dev environments and not included in your project, unless you depend on say some funny version of boost.

how to handle lib include paths in my modules (environmental variable, relative paths, git submodules, etc. ) ?

This is what your build system - CMake - is for. Your source code just has #include <third_party_lib.h> without worrying about where they are located.

should I always build external libs from source or just used their binaries ?

Prefer binaries by default, unless you have a good reason to build from source every time.