in reply to Using punctuation to split a text

The following could get you started. Cheers. 
use warnings;
use strict;

my $SPACER = "\n\n";

while (my $line = <DATA>) {
    $line =~ s|^\s+||;  ## trim leading whitespace
    $line =~ s|\s+$||;  ## trim trailing whitespace
    $line =~ s|([.?!]+)\s*|$1$SPACER|g;       ## break at [.?!]
    $line =~ s|([a-z])([A-Z])|$1$SPACER$2|g;  ## break at camelCase
    print $line . $SPACER;
}

[download]
__DATA__
The Tell-Tale LiverEdgar Allen MyselfFALSE! nervous I had been and am;
+ but am I mad?   The disease had sharpened, not destroyed my senses..
+.   Above all was the sense of hearing acute.How then am I mad?!     
+    Hearken! and observe how calmly, I can tell you the story.

[download]
prints: 
The Tell-Tale Liver

Edgar Allen Myself

FALSE!

nervous I had been and am; but am I mad?

The disease had sharpened, not destroyed my senses...

Above all was the sense of hearing acute.

How then am I mad?!

Hearken!

and observe how calmly, I can tell you the story.

[download]

In Section Seekers of Perl Wisdom