Complete rewrite of the syncml core engine to make it scallable
Remaining work :
- review of conflict management
- re-implement splitting of big object
- generic unit test for AsynchronousEngine
- complete review of default conduit
- lot of TODO and XXX in the code to check

Now title needs to be configured as a content translation translated property
to be able to search on title.

I doubt anyone wants to fill full_text table with this information.

It's no longer needed to configure using the script

-Titlecase terms, uppercase abbreviations, avoid jargons, add titles to empty title forms....

* it is faster.
* it does not require Products.

Allow client side to specify how it want server to return listbox field - i.e. it can be rendered locally or rendered entirely server side.

Fixes copy-paste of DateTimeField rendering into search expression, as it
separates time from date with 3 spaces.

Original code behaviour:
>>> def foo(self, a=None):
...    return 'works'
...
>>> context.foo(a=1)
works
>>> def foo(self, a):
...   return 'works'
...
>>> context.foo(1)
works
>>> context.foo(a=1)
TypeError: foo() takes exactly 2 non-keyword arguments (0 given)

New behaviour fixes this TypeError, to be closer to normal python
behaviour.
Also, original code was doing expensive checks before cheap ones.

Also, use from ... import * to make verbatim original code work.
Also, use original code's coding style for unaltered lines.

For easier copy/paste from original file.

Implement properly portal status message gadget to be a global one and support showing message from URL.
Implement properly DateTimeField.

This avoid having some failures of testnodes