In order to stabilise it zodb path has to be calculated early.

It seems that <= works only for one section (parameters from deeper sections)
are not available on top one.

This reverts commit 6a1dc3da.

It seems that more then one section with <= is not supported correctly.

Storage name does not map required file name.

In order to simplify generation, do not care yet about -instance suffix.

Zeo driven configuration is capable to generate Zope connection strings. Handle
global Zope related keys.

Turn on offline mode, reuse eggs.