Update ATmega1284P.hh

to access pins D15 & D16
Update PinChangeInterrupt.cpp

base is given by parameters from the macro later
Update PWMPin.cpp

COM1x0 enable both, direct & complementary PWM output. COM1x1 only the direct one.
Merge pull request #253 from thomasahlendorf/patch-3

Update PWMPin.cpp
Merge pull request #251 from thomasahlendorf/patch-1

Update ATmega1284P.hh
Merge pull request #252 from thomasahlendorf/patch-2

Update PinChangeInterrupt.cpp