Update Android port

Update Android port

* doc/emacs/android.texi (Android Windowing): Reword
documentation.
* java/org/gnu/emacs/EmacsActivity.java (EmacsActivity):
* java/org/gnu/emacs/EmacsContextMenu.java (EmacsContextMenu):
* java/org/gnu/emacs/EmacsFontDriver.java (EmacsFontDriver):
* java/org/gnu/emacs/EmacsSdk7FontDriver.java
(EmacsSdk7FontDriver):
* java/org/gnu/emacs/EmacsService.java (queryBattery):
* java/org/gnu/emacs/EmacsWindow.java (EmacsWindow): Make
functions final and classes static where necessary.
* src/android.c (struct android_emacs_service): New method
`display_toast'.
(android_init_emacs_service): Load new method.
(android_display_toast): New function.
* src/android.h: Export.
* src/androidfns.c (Fandroid_detect_mouse):
* src/androidselect.c (Fandroid_clipboard_owner_p)
(Fandroid_set_clipboard, Fandroid_get_clipboard)
(Fandroid_browse_url): Prevent crashes when called from
libandroid-emacs.so.
* src/androidterm.c (handle_one_android_event): Fix out of date
commentary.