Renaming field contam to internalContam

[GusRiva]

The problem

Our metadata file has two related fields contam and extraStemmContam.

extraStemmContam has some ambiguities, as we saw here: #176 (comment)
However, it is clear that it represents a sort of contamination from a node that is not descendant of the archetype. So that is not a problem right now. The question is about contam. This field is ambiguos:

1- It could mean only contamination among the nodes of the descendants of the archetype (the main tree depicted in the image).
2- It could be the general class that includes both contamination among the nodes of the tree (point 1) and also the extra stemmatic contamination (extraStemmContam). So the fields would answer the questions: is there any kind of contamination (contam)? If yes, is there extra stemmatic contamination (extraStemmContam)?

I think the correct way to do it would be option 1: contam is only internal. The reason is that with option 2 we encounter two different cases that are indistinguishable:
a- There is only extra stemmatic contamination.
b- There are both internal and external contaminations.

If we follow the meaning of 2 these two cases would be the same:

contam: "yes"
extraStemmContam: "yes"

However, if we follow the meaning of 1 they would be different:
a:

contam: "no"
extraStemmContam: "yes"

b:

contam: "yes"
extraStemmContam: "yes"

Proposed solutions

1. Make it more clear in the documentation that contam only refers to internal contamination

2. On top of the changes in the documentation, rename the field contam to internalContam or something similar to make more clear.

See #176 (comment) for the original comments on this.

[Jean-Baptiste-Camps]

In addition, should we have something different (new field?) for "intertextual contamination", when elements are borrowed from the tradition of another text ?