add Base_dirs.state_dir, on linux it uses $XDG_STATE_HOME and default to $HOME/.local/.state on macOS and Windows it's equivalent to Base_dirs.cache_dir ; add Projects_dirs.state_dir
0.4 - 2021-11-25
rename module Common to Directories_common
0.3 - 2021-03-31
use ctypes.stubs instead of ctypes.foreign on windows