Solver scales very badly

[erickim555]

To replicate: Add the following chords: C, C, C (all tonic).

The solver will take way too long to generate the solutions, even though the input is very small.

[erickim555]

[Partial Fix] The slowdown was due to the Grader asking for a large number of solutions, and then sorting them by grade.
A quick and dirty fix is to have the Grader only consider at most a relatively small number of solutions (ie 200).