GSL ODE-solver bugfixes

[Brian Gough]

Tuomo Keskitalo writes:
 > I've put some effort on fixing GSL-1.5 ode-initval bugs #5 (broken
 > error terms) and #17 (failure recovery during ODE step), among other
 > things. The work is not yet finished, but I hope it is at sufficient
 > state for getting comments. I would appreciate if somebody who knows
 > the ODE-solver field would take the time to review my code and comment
 > on it. 

Thanks for those, I've now added this code to the cvs repository.

-- 
Brian Gough