First draft of wdt.h / power.h / sleep.h reorg:
        * include/avr/wdt.h, include/avr/power.h, include/avr/sleep.h:
        Use new and old macros to allow for new devices.
        * include/avr/power-clkpr-1.h, include/avr/power-clkpr-2.h: New files.
        * include/avr/power-clkpr-3.h, include/avr/power-clkpr-4.h: Likewise.
        * include/avr/power-clkpr-5.h, include/avr/power-clkpr-6.h: Likewise.
        * include/avr/power-clkpr-7.h: Likewise.
        * include/avr/sleep-1.h, include/avr/sleep-2.h: Likewise.
        * include/avr/sleep-3.h, include/avr/sleep-4.h: Likewise.
        * include/avr/sleep-5.h, include/avr/sleep-6.h: Likewise.
        * include/avr/sleep-7.h, include/avr/sleep-8.h: Likewise.
        * include/avr/sleep-9.h, include/avr/sleep-10.h: Likewise.
        * include/avr/sleep-11.h, include/avr/sleep-12.h: Likewise.
        * include/avr/sleep-13.h, include/avr/sleep-14.h: Likewise.
        * include/avr/sleep-15.h: Likewise.
        * include/avr/io?*.h: Apply changes generated with
        gen-avr-have-xxx branch.
Move include/avr/io?*.h include guards to file end.
Remove files that got accidentally added.