Sorry for going back and forth with constness, but in some cases it was impossible to ensure that input params aren't overwritten, thus I took const away to avoid making promises that can't be met (see the case of fetch that uses a supposedly input-only param to return data). Overwriting memory that was declared const initially is a serious error in C++ with undefined outcome so we better do not lie.
2. Introduce new private API calls, fb__shutdown() and fb__shutdown_callback().
3. Introduce fb_smp_server - binary to run superclassic on posix.
4. Various cleanups.
placed some variables in context
fixed some function signatures
closed a few possible buffer overruns
sorry to the platform maintainers, I can't verify what I did for non-Win32 builds
