VGLII version 3.1.3 released - bug fix & new problem file

[Brian White]

Hi all
Sorry for all the e-mails, but there was one more (and I hope the
last) bug in VGLII. When you saved for grading, it gave the filename
as "null". I fixed that. I think this should be the last bug until I
do more revisions. Thanks to Stefanie Baker for finding this. Thanks
to all of you for your patience with all the new versions.

Also, at the request of Sophie Javerzat, I added a new problem file,
TwoGenes06.pr2. It has two unlinked autosomal genes; one is simple
dominance; the other is incomplete dominance. I really liked Sophie's
reason for this problem: This is because when 2 genes segregate
independently, students have learned that F1xF1 should give the famous
mendelian 9:3:3:1. So when they see 9:3:3:1 as a result of a cross,
they skip the demo that there are 2 genes in the first place
(analysing one trait after the other) and it is difficult to make the
difference between a student that is aware of the meaning of 9:3:3:1
and one who just learned it without understanding the relation between
meiosis and progeny. With this new set up, which they have not seen in
lectures, they really have to go one step after the other. First they
see there are 6 populations which is going to be challenging because
they will REALLY question the number of genes: 2, 3, more? So they'll
be forced to analyse one trait then the other, extract the codominance
from this then predict the values for independency ie: 1/16; 1/16;
2/16; 3/16; 3/16; 6/16. This they don't know beforehand, so it is more
them building up the model rather then finding back some known
formula...

Thanks, Sophie!

Enjoy!

Brian