Caller might try to log the transmission XMLs and raising would result in
aborted transaction.

otherwise imagemagick will create black-background image when resizing.
http://studio.imagemagick.org/discourse-server/viewtopic.php?f=3&t=19677

In case of failure, reserved messages were freed before finalization.
This was useless because finalization frees them and dangerous because another
zope could start processing a message that should not be executed again.

In other parts of ERP5 we do not specify it. As image resolution
should be handled as a system preference (as other image properties like quality, format, etc..)
do not specify it any more in generated
UI image links. Just let system use provided defaults.

- Remove acquired permissions

If pre_converted_only is True system will return desired conversion only if it's already cached.
Extend testDms to cover it.

Allows FormBox to contain fields outside "left" group.
The use of this is most evident when FormBox is in the "bottom" group: it
allows included form to have field groups with borders (left, right,
center) or without borders (bottom), hence allowing competely extending
base form. This required rewriting JS code stitching "left" & "right"
groups together so it honours nesting.
For backward compatibility, hide "left" groups rendered inside any bordered
group - but only when there is no field in "right" group.
Also, clean up duplicated code in embedded_form_render and use proper
naming (templates used by forms should always end with "_view").

And add a test checking this in portal_rules

- PEP 308: Conditional Expressions
- PEP 341: Unified try/except/finally
- PEP 343: The ‘with’ statement

Checked following occurrences in comments:
- "Python 2.[456]"
- "Zope 2.[891]"
- "BBB"
- "BACK"

Checked uses of:
- email, hashlib, numpy & tarfile (modules)
- ImportError
- string.Template
- suppress_events (parameter of _setObject)

Excluded:
- some forked modules (MailTemplates, PortalTransforms...)
- some i18n compatibility code

This allows to Specify a random sleep time (with 'sleep' parameter) to
get more realistic results. Update the example accordingly.