paper: preserve whitespace on description instead of adding breaks
This preserves the indentation of text in the changeset description.
This is useful for example for descriptions containing command line
use case examples like:
$ hg -q heads
13934:648a834cca14
13912:71ea5b2b9517
Without this patch, such space-char indented text was just left aligned.
(binary:application/octet-stream)