CNF Encoded Isomorphic and Optimized Miters from Hardware Model Checking Competition 2020 Models

From the Hardware Model Checking Competition 2020 we have collected 324sequential model checking problems and for each generated an isomorphic andan optimized miter. The isomorphic miters just compares two identicalcopies while for the optimized miter one copy went through optimizationwith ABC using the `dc2` command. The CNFs are generated with a new version of `aigtocnf` which detectsXOR and ITE gates in the AIGER circuit and if detected uses a more compactencoding (4 clauses clauses instead of 9) for each detected gate.