[BioPython] Biopython 1.21 released

[Jeffrey Chang]

Hello everybody,

I've made Biopython 1.21 available on the website at:
http://www.biopython.org/download/

Martel was inadvertently left out of the Biopython 1.20 distribution.  
This release corrects that problem.  Also incorporated in this release 
is:
   Martel added back into the released package
   new AlignACE module by Bartek Wilczynski
   Andreas Kuntzagk fix for GenBank Iterator on empty files

Many thanks to everyone who noticed the Martel problem and reported it!

Jeff