Improved graphics for the second presentation in session 2- Session 2: CRM Tickets and Events - Tickets

Improved graphics for Session 2: CRM Tickets and Events - Events, and some updated workflow for session 1

Otherwise this is interpreted as text/html after sending html emails

knowledge_pad/worklist gadget: support displaying a worklist that does not respect the (%(count)s) convention

* Worklist must include (%(count)s) to include the number of document in that worklist
* The role of users who have to take care of the documents must be defined on the worklist

There's no magic in this patch series: it is known that HBTreeFolder2 has
limitations about the ids that can be set without conflict, and this can't be
fixed without causing compatibility issues with existing data.

The patches contain:
- some optimization
- bug fixes
- detection of id conflicts before causing data loss

This will also allow us to use a newer version of ZODB. Recent BTrees failed
on the following line of `_setOb`:

        if len(id_list) == 1 and not htree.has_key(None):

(None is not valid key for comparison since
 ZODB commit bb5aac21277f43333d6450064dc6670c8c280e40)

The long story about id conflicts is that a HBTreeFolder2 can't store 2 objects
<A> and <A>-<B> where <A> does not contain '-', and that's the rule followed by
_getOb/_setOb/_delOb. However:
- Conflicts are detected by testing the type of the value, which means
  HBTreeFolder2 can't store values of the same type as the one it uses
  internally (i.e. OOBTree).
- For performance reasons, _htree_iteritems and getTreeIdList use a stricter
  rule: they assume there can't be 2 objects <A> and <A>-<B>, regardless of the
  presence of a separator in <A>. Maybe this rule should be enforced in _setOb.

/reviewed-on nexedi/erp5!112

It was an unefficient adaptation of BTreeFolder2 code.

These methods have probably never been used.

getTreeIdList is still required by Folder_reindexAll.
getTreeIdList is not immediate anymore but the reindexing of a folder should
anyway be reimplemented to not depend on this method: only one tree is indexed
at a time, which is unefficient when they're small.

_getOb and similar methods are reimplemented in a faster and safer way.
It now checks it is only used to return leafs.

Similarly, _delOb now refuses to delete trees at the root.

__getattr__ wrongly returned wrapped results (__of__).

Since commit 055d0a69
("HBTreeFolder2: make object{Ids,Values,Items} really lazy"),
_fixCount() does nothing because objectIds() was optimized in a way that
len(self.objectIds()) already returns self._count()

Callers up the stack should not mutate returned value (and all callers
found in this repository code follow this rule).
Saves a list copy and an extra call on each call, and a few lines of code.

work partially done by Vincent Pelletier (z_get_table_schema)

@Tyagov, please, check the demo notebook added.



/reviewed-on !145

erp5_web_renderjs_ui: add a common gadget to render multi&relation field & no need to show "Create:X" string

/reviewed-on nexedi/erp5!140