Allow reification transformations

[goodmami]

Reification is a constrained graph transformation that replaces an edge with a binary node. For example, A --> B becomes A <-- C --> B. This allows cycles to be broken and relations to become focused (e.g., as root nodes). Not any edge can be reified, and the new node and new edges are not all the same.

• See if there's a more complete table than the one at https://github.com/amrisi/amr-guidelines/blob/master/amr.md#reification
• Create a machine-readable (CSV, JSON, etc.) version of the table (if one doesn't already exist)
• Create methods for, e.g., reify() and the inverse (dereify()? deify()?)

Hopefully reification can be done on a Graph without knowledge of the codec.

[goodmami]

For the table, also see https://www.isi.edu/~ulf/amr/lib/roles.html#tables

[goodmami]

Resolved by ce402f0