plot-aesthetics, fixes for RNA-Seq, more depth diagnostics

v0.1.2

• allow lower-case reference alleles in case of masked genomes (see #5)
• set relatedness values < -1.5 to -1.5 in the plot
• fix bug that affected relatedness calcs especially in RNA-Seq
• add more diagnostic values (allele-balance and number of non ref/alt bases)

see previous release for sites file. For hg38, it's possible to use: https://github.com/brentp/peddy/blob/master/peddy/GRCH38.sites
(if your chromosomes have the 'chr' prefix, that must be added to this sites file).