It is possible that a private person is linked to in a tiddler with the
syntax `[[Jane|MsJaneDoe]]`.
Up to now, the text of the link was not redacted, which could lead to
unintentional privacy leaks.
Therefore, a new parameter `replace_text` is introduced for the
`replace_private_people` builder.
When that is set to True, then the link text is also replaced with the
initials.
Signed-off-by: Jacob Kiers <code@kiers.eu>