SabreDAV migrate script for version 3.0

This script help you migrate from a pre-3.0 database to 3.0 and later

Changes:
  * The propertystorage table has changed to allow storage of complex
    properties.
  * the vcardurl field in the principals table is no more. This was moved to
    the propertystorage table.

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