Add try/catch in Atlas/resolveConstraints

Users with student licenses for SNOPT were getting "Maximum column size
exceeded" errors when Atlas/resolveConstraints was called.
`checkDependency('snopt')=1` in these cases, but the problem is too big for the
limited license. Now, if the initial call to resolveConstraints fails, we try
again using 'fmincon'.

Resolves #415