build_right_clusterplot: Right intra-cluster linkage plot
Description
build_right_jitterplot() builds a horizontal plot displaying the mean
pairwise R^2 linkage between each SNP and all other SNPs in its marker group,
grouped by marker group, coloured by alternate allele frequency. Makes use of
the $Varfile information from haplotyping object. It is an internal function
called by crosshap_viz(), though can be called separately to build a
stand-alone plot.