SabreDAV migrate script for version 2.0

This script help you migrate from a pre-2.0 database to 2.0 and later

The 'calendars', 'addressbooks' and 'cards' tables will be upgraded, and new
tables (calendarchanges, addressbookchanges, propertystorage) will be added.

If you don't use the default PDO CalDAV or CardDAV backend, it's pointless to
run this script.

Keep in mind that ALTER TABLE commands will be executed. If you have a large
dataset this may mean that this process takes a while.

Lastly: Make a back-up first. This script has been tested, but the amount of
potential variants are extremely high, so it's impossible to deal with every
possible situation.

In the worst case, you will lose all your data. This is not an overstatement.

Usage:

php  [pdo-dsn] [username] [password]

For example:

php  "mysql:host=localhost;dbname=sabredav" root password
php  sqlite:data/sabredav.db