- new approach uses a new controller gadget
- old one is kept for backward compatibility (not migrated apps)

For example, if property_sheet "prop" was moved from BT 1 to BT 2 and BT 1 doesn't exist anymore.

Before this commit we have this order:
1.  install BT 2 ("prop" exist and isn't touched)
2. remove BT 1 ("prop" is removed)
=> at the end "prop" doesn't exist anymore

After this commit we have this order:
1. remove BT 1 ("prop" is removed)
2. install BT 2 ("prop" is readded)
=> at the end "prop" exists and is OK

/reviewed-on nexedi/erp5!866

old key was simply "id" so when a container is a VirtualFolder (like Web
Site), container._getOb("id") can return any object with id "id"
including an object outside the container.
    
Change the key to contain PhysicalPath of the container to get only
objects inside the container.
    
This actually fixes installation of some business templates with Web
Site inside.

/reviewed-on !867

1.auto centre for image
2.table line is centered
3. image option is left-margin 3cm under image

Not all lock uses in this code fit context managers, but use them where it
does.

Add 10 seconds timeouts on all blocking calls in this test method, which
should be a thousand times more than required on a slow machine but avoids
completely blocking tests.

Even though it should not raise, a stale lock would be a serious issue.

The intent is to be able to tell that an independently-defined group of
activity nodes may execute given activity, and no other node.
This allows more flexible parallelism control than serialization_tag.

Divide conflict hot-spot to improve write performance: now, conflict risk
will not be proportional to the number of zope processes, but only to the
number of threads within considered process (...because there is no
stable thread name, if there is one day and conflict splitting is needed,
it will be easy to implement: just concatenate that name to node name in
FragmentedLength._map).
Automatically migrate to FragmentedCount on containers larger than 1k
objects (this threshold may evolve).

Provide a way to generate ids on specific documents when they make sense.
Reduces the risk of conflicts that portal_ids's in-ZODB id generator
creates.
Reset generator state on any copy (both copy/pase and clone), but not on
move (cut/paste and setId).

These two classes inherits from two classes implementing CopyContainer API:
- ours, via low-priority bases
- another one, via higher-priority bases, because these classes need
  some non-ERP5 methods to override ERP5 methods.
So after defining these classes, resolve inheritance priority by binding
all CopyContainer methods provided by their ERP5 base class, overriding
the ones provided by their non-ERP5 bases while still allowing their ERP5
base class to override the CopyContainer method.

Allows for safe migration to another id generator, by preventing silent
success of any piece of code still using the former generator, allowing
its detection and resolution before duplicate ids are emitted.
As a consequence, also allows on-demand and partial migration of id
generators.

- erp5_web: new actions and forms for text editor migration
- erp5_officejs_connector: new jio view for Web Page Module (text editor
main list-page)