Reconsider TruthTable serialized format

[cerebis]

The class TruthTable is serialized to disk using YAML. This mapping to text is possibly not ideal as it currently contains implementation details in the form of class references.

E.g.

scaffold_0: !Assignment {mapping: {A: 0.994, B: 0.991, C: 0.987, D: 0.985}, weight: 2226}
scaffold_1: !Assignment {mapping: {A: 0.993, B: 0.994, C: 0.990, D: 0.988}, weight: 2202}

The class Assignment is confounding to tools which may not wish to adopt our particular codebase.

A better version would be plain mapping, with the details for instantiation contained in our codebase.

E.g. without class type references

scaffold_0: {mapping: {A: 0.994, B: 0.991, C: 0.987, D: 0.985}, weight: 2226}
scaffold_1: {mapping: {A: 0.993, B: 0.994, C: 0.990, D: 0.988}, weight: 2202}

and further without member variable references.

scaffold_0: { {A: 0.994, B: 0.991, C: 0.987, D: 0.985}, 2226 } 
scaffold_1: { {A: 0.993, B: 0.994, C: 0.990, D: 0.988}, 2202 }

or lastly as a table

scaffold_0 2226 A:0.994 B:0.991 C:0.987 D:0.985
scaffold_1 2202 A:0.993 B:0.994 C:0.990 D:0.988

[cerebis]

With a little experimentation, I've decided to go with the first example.

scaffold_0: {mapping: {A: 0.994, B: 0.991, C: 0.987, D: 0.985}, weight: 2226}
scaffold_1: {mapping: {A: 0.993, B: 0.994, C: 0.990, D: 0.988}, weight: 2202}