Implement Padded SGM algorithm

[SHAAAAN]

functionality

Input Graphs G1 and G2 with respective vertex sets {1,...,n_1} and {1,...,n_2} and with respective adjacency matrices A and B, and suppose n_1<n_2, use the SGM function to the padded A and B, then return the restriction of permutation matrix to the vertices of G1.

The output can be compared with Figure 3 in paper seeded graph matching: https://arxiv.org/pdf/1209.0367.pdf.

[bdpedigo]

@SHAAAAN if you still have code/experiments for this in any form, would you mind just linking them here?

[SHAAAAN]

Sure. Here is what I have done so far.
https://github.com/SHAAAAN/MyGraspy/blob/master/codes/padding.ipynb
I met some problems when I tried to merge it with the original SGM algo. Hope this is useful for other talented people~

[bdpedigo]

Thanks so much Shan! Hope all is well for you

[asaadeldin11]

I have some code for this so I can take this. Would be a relatively quick fix once QAP is in scipy (#348).