Invoice Export; multi-line charge descriptions cause issues with CSV type files

CSV type Invoice Export files do not handle multi-line charge descriptions properly. They output the line including the raw newline characters, which means the outline line is split over two lines. This causes the file import to be rejected.

File exports affected:

emPOWER File
Performer
MYOB (all versions)
Quickbooks
Xero

All of these file formats now output two spaces in place of the new line. The exception is "emPOWER File" where it outputs "{NewLine}" instead, which the import interprets back as a new line.