Toy MC for unit tests

[robertdstein]

Is your feature request related to a problem? Please describe.
I'm always frustrated when bugs turn up involving MC, as these are not currently covered by unit tests.

Describe the solution you'd like
A small toy MC dataset, with the same structure as the proprietary IceCube MC, should be made and be included as package data. Unit tests should cover these cases.

Describe alternatives you've considered
Not doing that. "Never making a mistake ever in coding" is an alternative solution, but the preferred one may be easier.

[robertdstein]

One alternative might be to copy/clone IceCube MC, or a subset of it, before unit tests by use of secret keys.