Improved handling of the ''preserve newlines'' rendering mode for Wiki text (follow-up to r1561)
It's not done by systematically appending a `[[BR]]` macro at the end of each line, but by appending `<br>` in the output, when needed.
Closes #7461.
Authored by: cboos 2008-07-25
Parent: [r7397]
Child: [r7399]
