Split Pg-database.sql in a schema part and a static data part

[ehuelsmann]

By having separate parts, some tasks get easier:

1. Developing test data sets, which can be dumped with the "Data only" switch to reduce size and be somewhat version agnostic
2. Admins can directly load dumped data from another database without having to remove conflicting data first

[ehuelsmann]

This was realized for most of the relevant data and will be released as part of 1.12.