Rename internal functions (#94) * fix : rename __play_winmm to _play_winmm * fix : rename __play_winmm_flags to _play_winmm_flags * fix : rename __play_winsound to _play_winsound * fix : rename __play_winsound_flags to _play_winsound_flags * fix : rename __play_google_colab to _play_google_colab * fix : rename __play_alsa to _play_alsa * fix : rename __play_proc_alsa to _play_proc_alsa * fix : rename __play_afplay to _play_afplay * fix : rename __play_proc_afplay to _play_proc_afplay * fix : rename __play_auto to _play_auto