If a column is explicitly resolved to a table, it cannot be resolved to
another later. This causes problems when writing a related key targeting
another table with the same column name.
This code duplicates work done in the (only) caller (in
SearchKey/RelatedKey.py), as it already registers the latest relation
table with the column to apply on it.

discussion thread view using passed from request new unindex discussion
post url.

Allow that not index (yet ) discussion posts to be show under a discussion thread view using passed from request new unindex discussion post url.

- some variables were designed for a single test suite, so create
  NodeTestSuite objects to store them (some logic was broken after
  the split of the long run method into several methods)
- remove some optimization that were trying to reduce a bit the
  load on master. This was adding complexity for little benefit
- take into account new status code from slapos.core

We cannot wait for the document to be created to introspect its properties,
because we need to pass the input parameters to newContent. Instead use a fixed
list of common parameters

Tolerate empty tables.

This was forgotten in commit 48212534
("Drop support for Zope 2.8").

- test node support much less parameters, it will get them from
  the master
- testnode get list of test suite to install
- the instance folder structure has changed to support multiple
  test suites
- test node will delete useless test suites data if needed
- the master url should be a sub object (distributor) inside
  the task distibution tool
- the long run method has been splitted in many smaller methods
  (it is still possible to go futher

 Scope only includes cloudooo, memcached and kumofs configuration for
 now.