gnu: r-seurat: Update to 2.1.0.
* gnu/packages/bioinformatics.scm (r-seurat): Update to 2.1.0.
[propagated-inputs]: Add r-diffusionmap, r-dtw, r-ggjoy, r-hmisc, r-ica,
r-mass, r-matrix, r-nmf, r-plotly, r-sdmtools, r-tidyr; remove r-plyr,
r-rcppeigen, r-fastica.