make fs_posix.h use native posix types, add file id to FsPosixAttrs, don't clobber MAX/MIN if they already are defined
add set_times method to fs interface and fs_posix
move away from user-specific interface files (instead of util_fs.c importing util_fs_fs.h, it now imports fs.h again), implement fs_dynamic for fusers of libwebdav_server_sockets_fs, make compatible with c++ users
fix mac config.mk, prevent _logging_cur_level from being a common symbol by explicitly initializing it (ranlib on mac doesn't export common symbols in static libraries by default)