[Halk]

I have some old txt files that I'm trying to switch to ebooks.

Many of them have sentences broken by carriage returns.
E.g.
"The sentence is fine, and in most cases paragraphs are in tact, but perhaps one
in every five sentences contains a carriage return in the middle, which is mildly annoying when reading on my Cybook."

The common factor is that there's a no punctuation before the carriage return. Is there any way to sort this out? I was thinking perhaps if I could get Calibre to delete any carriage returns that were not preceeded by .!? or ." !" ?"