Collective.behavior.talcondition

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- Add Transifex.net service integration to manage the translation process.
[macagua]
- Add Spanish translation
[macagua]
- Do not consider the `archetypes.schemaextender` on Plone5.
[gbastien]
- Adapted code (except, implementer) to be Python3 compatible.
[gbastien]
- Added parameter `trusted=False` to `utils._evaluateExpression`, this will use
a trusted expression handler instead the restricted python default.
[gbastien]

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- Added parameter `raise_on_error` to `utils.evaluateExpressionFor` to raise an
error when an exception occurs instead returning False.
[gbastien]
- Added method `TALCondition.complete_extra_expr_ctx` to the behavior to
formalize the way to get `extra_expr_ctx` to avoid the `evaluate` method
to be overrided.
[gbastien]

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- Do not break if parameter `expression` passed to
`utils._evaluateExpression` is None.
[gbastien]

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- Added new parameter `error_pattern=WRONG_TAL_CONDITION` to
`utils.evaluateExpressionFor` and underlying `utils._evaluateExpression` to
be able to log a custom message in case an error occurs during
expression evaluation.
[gbastien]

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- Mark elements using behavior with `ITALConditionable` interface so it behaves
like element using the AT extender.
[gbastien]

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- Use CheckBoxWidget for `ITALCondition.roles_bypassing_talcondition` to ease
selection when displaying several elements.
[gbastien]