Added new elements, removed redundant

The initial schema I created was before the requirements were posted, so it contained several sample elements like "Place" and "PlaceID", as well as sub-elements like "Born" and "Office" for persons, etc. I've cleaned these up and added elements exactly as mentioned in the requirements on the project page.

Additional changes:
- Removed Place container type and PlaceID completely, since it adds to complexity and isn't a requirement. Replaced it with a list of plain-text "locations" that are a sub-element of Crisis
- Added Keys and keyrefs for all three types (Crisis, Person, Organization).
- Added three new types: CrisisWithID, PersonWithID, OrgWithID to contain these keyrefs as attributes, specified using xpath.
- In addition to each Crisis containing related Orgs and People, each Organization needs to contain related Crises and People, and each Person needs to contain related Crises and Orgs. This is because each of these relations are many-to-many.
- Added all other elements under Crisis, Person and Organization mentioned on the project page. All sub-elements except references to Crises, Orgs and People now have minOccurs=0 to allow missing values.
- Added an "any" element at the end of all three containers to allow extra elements to be added in XML.
- Added a ListType container, in which each element can contain optional hyperlinks, embed links as well as plain-text (text to be displayed on page). This is meant to be a generic data type that can accommodate all kinds of data.
- Added a Common type container, which contains elements common to Crises, People and Orgs {Citations, External Links, Images, Videos, Maps, Feeds}, each of type ListType.
- Attempted to create a standard for storing URLs for embedded objects (images, videos, maps, feeds) in the elements of ListType, considering the inability of ElementTree to read [!CDATA.. or mixed content. See comments on example XML for details.

I also had to write the example XML from scratch because I didn't have any other sample data for all the new fields..

These are a lot of changes, and all are open to discussion. Let me know what you think.
Sorry for making all changes in one go.. if anything needs to be modified I can commit on top of this.