GeezerVison

…st round-trips

plistlib's _escape() function was normalizing \r\n to \n and \r to \n
during XML plist serialization. When the plist was loaded back, the
original carriage return characters were lost because expat also
normalizes newlines in XML character data.

Fix by encoding \r as the XML character reference &python#13; instead of
converting it to \n. Character references are not subject to XML
newline normalization, so expat correctly decodes &python#13; back to \r,
preserving the original data during round-trips.