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.
* tz-link.htm: Update info about Microsoft Windows.
* tz-link.htm: Consolidate and tighten up Windows description.

* NEWS: Mention Windows-related doc changes.
Improve checks for white space.

* Makefile (check_white_space): Rename from check_tabs; all uses
changed.  Also check for trailing white space and for oddball
ASCII white space characters.
Shift the load a little between the two tarballs.

(Thanks to Alan Barrett for the suggestion.)
* Makefile (SOURCES): Move workman.sh here, from $(MISC).
(COMMON): Move NEWS here, from $(DOCS).
(tzdata$(VERSION).tar.gz): Move $(MISC) here, from
tzcode$(VERSION).tar.gz.
* NEWS: Document the above.
* europe: Fix some broken British URLs.  (Thanks to Lester Caine.)

* NEWS: Document this.