disabling Eigen asserts

#### Summary:

Disables Eigen asserts at compile time.

#### Intended Effect:

This should disable Eigen's run-time asserts. We should be catching all places this pops up, so if this triggers segmentation faults, we will need to add more checks to our error checking.

#### How to Verify:

See changed makefile.

#### Side Effects:

This may cause seg faults where we haven't been careful. As far as I know, there are no known places where this happens.

#### Documentation:

None.

#### Reviewer Suggestions:

@bgoodri