Provide additional placeholders in email templates

[Andreas Purde]

A user requested the following:

1.) Page is moved: The variable "$watchLink" contains the link to the watched page tree where the page was before it was moved. There is no variable for the "receiving" new page tree. However, this info would be helpful and should be retrievable via a separate variable.

2.) When watched pages are moved to a page tree that is not watched, the variable "$watchLink" is obviously set to the same value as "$addedLink". Here, if possible, the value should be output to the new parent page in "$watchLink".