* zfs.py: treated received properties as local and added diff mode support
If you use "zfs set" to explicitly set ZFS properties, they are marked as from source "local". If ZFS properties are implicitly set by using "zfs send" and "zfs receive", for example as part of a template based installation, they are marked as from source "received". But as there is no technical difference between both types of them, the “received” ZFS properties should also be considered “local”. Otherwise Ansible would detect changes, which aren’t actual changes. Therefore I changed line 202/207 to reflect this.
For us it’s quite important, that Ansible modules support the diff mode in order to qualify changes. Therefore I added some code lines to address this.
* added changelog fragment for PR #502
* fixed typos in changelog fragment for PR #502
* minor changes in changelog fragment for PR #502
* added link to pull request in changelog fragment for PR #502
* extended the diff data structure to always include the name of the zfs filesystem
* added code to also maintain the diff data structure after a change
* reverted back some code lines for better code readability
* added an extra dict in the diff data structure to hold the zfs properties
