[Developers] sd_report object

[Mark Maunder]

See below

Hey Mark-

Before Version 10, variances and an std file would be calculated even if 
there were problems estimating an sd_report object, as long as the 
Hessian for the parameters was estimated and you could look at the std 
file to find the offending sd_report object.  As far as I can tell, in 
Version 10, a problem in an sd_report object means no std file.