Heatmap tools in SEtools package

[antagomir]

The SEtools package provides SE integration for pheatmap and ComplexHeatmap packages, see the vignette.

Consider whether this would be useful to update/improve the current heatmap plotting examples in OMA. They rely on the same packages but this seems to provide added capabilities for SE objects.

Also includes the do.scale argument to scale heatmap rows, which correspond to the Z transformation that we so far did as a separate step for heatmaps.