Don't throw with "Division by zero" if it's treatable

[Willi Braun]

Change the division by zero thrown, so that it is only checked
for accepted step like an assert, since while the initialization
or the non-linear solver process we should be able to try also
not suitable solutions.

class M
  Real x,y;
equation
  x = cos(y);
  y = sin(1.0 / x);
end M;

[Martin Sjölund]

I think this is working now. Can you confirm we fixed this?

[Martin Sjölund]

Postponed until 1.9.1

[Willi Braun]

yes, it's fixed!