Include OpenDocument formats in defaults

Now that OpenDocument is an ISO standard (see this document) and since StarOffice/OpenOffice are growing in popularity I'd like Drupal to support these by default.

The motivation for this came from a thread on Groups.drupal where some data was attached in the XLS format because - aside from txt - that's all that can be attached.

The OpenDocument Wikipedia entry lists the following document types:

• .odt for word processing (text) documents
• .ods for spreadsheets
• .odp for presentations
• .odg for graphics
• .odf for formulas, mathematical equations

I propose that we include the Word processing, Spreadsheet, and Presentation formats.

I targetted this as a feature for Drupal6, but since it is so small and implements ideas from the mission I'd be happy if someone decided it deserved to be in Drupal5.

Attached patch adds those document types without changing any currently approved document types.