So far, when a 'diff' dict is returned with module results, it is
checked for 'before' and 'after' texts, which are processed in
_get_diff() by python difflib. This generates the changes to display
when CLI users specify --diff.
However, some modules will generate changes that cannot easily be
expressed in a conventional diff. One example is the output of the
synchronize module, which presents changed files in a common log format
as in `rsync --itemize-changes`.
Add a check for a diff['prepared'] key, which can contain prepared diff text
from modules.
5b293b56d6