Allow to use CHOLMOD with 'long int' integer type
CHOLMOD supports this, it just wasn't exposed in the interface. It is needed for large problems.
This MR contains a unit test for the new feature, but that test only checks the interface. To test whether the feature really works you would need to use a very large matrix, which is supposedly not suitable in a CI context. I did test the code with a large matrix in my application, though.
Edited by Oliver Sander