New feature: Address Format

We suggest to have address format in LDML specification, to deal with the
cultural diversity of address. The format can be as follows:

<address>
<addressSegments>
<addressSegment type="country">
<label>Country/Region</label>
<mandatory>yes</mandatory>
</addressSegment>
<addressSegment type="state">
...
</addressSegment>
<addressSegment type="city">
...
</addressSegment>
<addressSegment type="street">
...
</addressSegment>
<addressSegment type="zip">
...
</addressSegment>
</addressSegments>
<addressOrder>stcyspzpcr</addressOrder>
<addressPattern>%st%nn%cy%nn%sp%bk%zp%nn%cr</addressPattern>
<states>
<state>Alabama</state>
<state>Alaska</state>
<state>Arizona</state>
...
</states>
</address>

Explanation of each tag:
addressSegments contain the address items that compose an address.

addressOrder is the order that an address should be displayed. For example,
"stcyspzpcr" means the sequence: street, city, state, zip code, country.

addressPattern contains the address order and other format information of an
address. For example, in en_US locale, there is a new line for most of the
address items, while in zh_CN locale, most of the address items are put together
consecutively. In the pattern "%st%nn%cy%nn%sp%bk%zp%nn%cr", 'st', 'cy', 'sp',
'zp', 'cr' are the same meaning as in addressOrder, while 'nn' means a new line
and 'bk' means a blank.

states are the states/provinces of the country. Each country has their own state
lists.