Log Message:
Update to 0.41

Upstream changes:
2017-04-14: Marc Bradshaw <marc@marcbradshaw.net>

 * commit aac893fdbaa7f8ccd5d37fa7f20d1785406cda51
   Author: Marc Bradshaw <marc@marcbradshaw.net>
   Date:   Fri Mar 17 14:53:53 2017 +1100
    Avoid use of $_ in read loop
    RT 106485: Mail::DKIM::PrivateKey->load tampering $_ and <FILE>

 * commit 06934f259e392b2a3cf94560e6051d9e522d0bf3
   Author: Marc Bradshaw <marc@marcbradshaw.net>
   Date:   Fri Mar 17 14:44:44 2017 +1100
    Ensure PrivateKey file is closed properly.
    Store PrivateKey file handle in lexical variable and close it
    once we are done.
    RT 120638: Mail::DKIM::PrivateKey does not close FILE

 * commit 9e7c1c4cb78a6cb1cf396ece4379c7ed2c44c974
   Author: Marc Bradshaw <marc@marcbradshaw.net>
   Date:   Fri Feb 27 12:08:11 2015 +1100
    Allow greater control over signed headers

 * commit 8291c034dc7db4394e9df80e70b8cbe8428a38c2
   Author: Marc Bradshaw <marc@marcbradshaw.net>
   Date:   Fri Jan 23 09:54:02 2015 +1100
    Allow greater control over which headers are signed by Signer