[distribution_list][CHG] Improve performance of 'get_distribution_list_ids' of 'distribution_list' model
[distribution_list][CHG] review code
[distribution_list][FIX] pep8 issue
[distribution_list][FIX] both post and same_thread fields do not exist anymore
[distribution_list][FIX] complete compatibility check, _get_computed_ids call inversion when not safe_mode
[CHG] string and set() operations improvements
[FLK8]
Merge pull request #13 from acsone/acsone-addons-distribution_list-improvements

[distribution_list][CHG] Improve performance