open(FILE, "<myfile.txt");
my $txt = do { local $/; <FILE>};
$txt =~ s/\n{3,}/\n\n/g;
close FILE;

$txt =~ s/\r|\n//g;
$txt =~ s/ /rand() < .5 ? ' ' : "\n"/eg;

open(FILE, ">myfile.txt");
print FILE;
print FILE $txt;
close FILE;