Feature: Allow card pass through

[MicahGale]

The idea is that when working on large problems (e.g., ATR whole core) you don't want to modify card formatting for parts of the file you aren't editing (e.g., the fuel geometry definition.

I think how to do this is to store all the original file lines (or read them JIT) with an input. All cards has a "mutated" flag. The MCNP file formatting function will only be called if the card has been mutated.

[MicahGale]

Working on this with !9.

[MicahGale]

Still will need to implement new unit tests for this feature.

[MicahGale]

mentioned in commit 01996be