'keep_existing' argument of Base._edit has never been used
and we should consider removing it.

When defining a guard on an object, calling
a method such as Base_viewDict on that object
could be denied due to guard acquisition.

- the check is moved to a less performance-critical place
- getPortalObject was forgotten in commit d8e9ed19

- 'apply' causes a break in cProfile results
- 'apply' is deprecated (removed in Python 3)

* reference
* translated_title
* the usual owner_title, creation_date and modification_date
* remove useless listbox_editable_fields that are defined in the field library

This business template does not seem to follow the guideline yet

For example, Python Scripts were:
- dirty in the imported BT (causing all of them to be reinstalled on upgrade)
- compiled to return None

When a currency exchange line is (in)validated, we need to reindex the currency exchange
cells that acquire validation state from the currency exchange line.

This allows defining an exchange rate without end date

https://codemirror.net/demo/activeline.html

since be31425e

not only complete python language words but also all words from the
buffer.

/reviewed-on nexedi/erp5!122

Mark the test as expected failure for now.

This test is in expectedFailure state and is still not passing with this
change, but this test was showing wrong example that can cause
confusion.