MoM: Refactor check for duplicate moments, fix display of results

As we have a working interface now, this commit improves the provisional handling of finding duplicate moments. Previously, indices for GMM were created, but this is not really needed. This commit cleans this up and similar to SMM makes use of the matched_moments block.

As a by-product of the previous provisonal handling higher-order moments for SMM where not correctly displayed as no labels were created. This is now fixed. The comparison of data moments and estimated model moments is also in the same ordering as the inputed orthogonality conditions in matched_moments.

Signed-off-by: Willi Mutschler <willi@mutschler.eu>