Update doc references to refer to CLDR and the page of CLDR codes where
appropriate - it used to say ISO country codes were used, but they aren't.
Also updated to refer to two *or three* letter language codes since they may be three letters (we use the shortest defined one for a language)
Updating comments about leadingDigits field at territory level as well.
Making function IsNumberGeographical public. This function operates on
the type of number and the country it belongs to only, so may have some
false positives.
Using this in the geocoder so that geocoding now limited to numbers that
we consider geographical, based on their type and country, rather than
just based on their type. The C++ geocoder did not previously check the
number type/country at all.
Indonesian and Chinese mobile numbers have now been added to the list of
possibly-geographical numbers.