This is not a very good solution, given that the standard allows "lines"
to be up to 1000 characters long. It is clearly stated that it is the
responsibility of the reader software to properly wrap lines to the
display format of the user. There was a recommendation to keep lines
short for compatibility with previously existing software, but this
was fifteen years ago. I am afraid that the failure to properly reflow
text must be seen as a serious flaw in software today.
A good reflowing algorithm is not very easy to implement, but it should
be the highest priority. The whole thing is complicated by the need
for reflowing text which has multiple levels of quoting. It is necessary
to separate out the initial quote markers before reflowing and to
reinsert them afterwards in the new lines. And lines starting with
certain character combinations should usually not be reflowed. Spaces
will usually indicate desired indentation, and - or # might indicate
some kind of structured list. 1. or 1: would be a section and so on.
In all, not a trivial job but one which is really needed.