Add tests for optimized iter_kmers path
Add tests for optimized iter_kmers path

Just copied the ones from the other path. These should be able
to be rejoined somehow if we can figure out an efficient way
to stride pandas dataframes

anderspitman/scikit-bio,anderspitman/scikit-bio,averagehat/scikit-bio,colinbrislawn/scikit-bio,SamStudio8/scikit-bio,jairideout/scikit-bio,gregcaporaso/scikit-bio,wdwvt1/scikit-bio,xguse/scikit-bio,jairideout/scikit-bio,colinbrislawn/scikit-bio,corburn/scikit-bio,jdrudolph/scikit-bio,wdwvt1/scikit-bio,demis001/scikit-bio,gregcaporaso/scikit-bio,demis001/scikit-bio,jdrudolph/scikit-bio,averagehat/scikit-bio,xguse/scikit-bio,SamStudio8/scikit-bio,kdmurray91/scikit-bio,corburn/scikit-bio,kdmurray91/scikit-bio