Adjust pre-1912 Portuguese transitions in the light of the 1911 decree.

(Thanks to Stephen Colebourne for a heads-up about the decree.)
* africa (Africa/Luanda, Africa/Bissau):
Change transition date to 1912-01-01.
(Atlantic/Cape_Verde, Africa/Maputo):
Add commentary about the switch.
* asia (Asia/Kolkata): Add commentary about Portuguese India.
* europe (Europe/Lisbon): Change Lisbon Mean Time from -0:36:32
to -0:36:45 (rounded from -0:36:44.68).
(Atlantic/Azores, Atlantic/Madeira):
Change transition date to 1912-01-01.
* NEWS: Document the above.