rabins rc14 division by zero

[Andreas Östling]

I was trying out ragraph for the first time but got this:
Floating point exception
no data

The Floating point exception message comes from rabins, and you get it 
when using rabins with any other -M mode than 'time', like:

$ ./rabins -r foo.arg
Floating point exception

$ ./rabins -M count 100 -r foo.arg
Floating point exception

$ ./rabins -M time 1m -r foo.arg
<data...>

The bad divison happens in ArgusAlignRecord():
 dsecs = ((start->tv_sec - nadp->startSecs) / nadp->offset) * 
nadp->offset;

The nadp struct is bzeroed on init and nadp->offset remains 0 unless you 
use time as mode. Perhaps it's the same bug as was reported in rc3 a 
couple of weeks ago. I'm not sure what the fix is as I'm not familiar 
with how rabins should work yet.

/Andreas