plotHeatmap: add --plotColors argument for profile plot line colors

[niekwit]

Allows users to set custom colors for the profile/summary plot lines when --whatToShow includes a plot. Colors are recycled if fewer are given than the number of lines. Accepts any matplotlib named color or hex value. Consistent with the existing --colorList approach.

Related to issue #1166.

Examples of how it works:

plotHeatmap -m matrix.gz \
	-out test1.png \
	--regionsLabel "Region1" "Region2" "Region3" "Region4" \
	--samplesLabel "WT" "KO" \
	--whatToShow "plot, heatmap and colorbar" \
	--perGroup \
	--heatmapHeight 10 \
	--heatmapWidth 5 \
	--colorMap viridis \
	--plotColors "#cccccc" "#dd3b3b"

Falls back to standard colours, if --plotColors is not used:

plotHeatmap -m matrix.gz \
	-out test2.png \
	--regionsLabel "Region1" "Region2" "Region3" "Region4" \
	--samplesLabel "WT" "KO" \
	--whatToShow "plot, heatmap and colorbar" \
	--perGroup \
	--heatmapHeight 10 \
	--heatmapWidth 5 \
	--colorMap viridis

Compatible with colour recycling:

plotHeatmap -m matrix.gz \
	-out test3.png \
	--regionsLabel "Region1" "Region2" "Region3" "Region4" \
	--samplesLabel "WT" "KO" \
	--whatToShow "plot, heatmap and colorbar" \
	--perGroup \
	--heatmapHeight 10 \
	--heatmapWidth 5 \
	--colorMap viridis \
	--plotColors "#cccccc"

Error message when invalid colour values are used:

plotHeatmap -m matrix.gz \
	-out test4.png \
	--regionsLabel "Region1" "Region2" "Region3" "Region4" \
	--samplesLabel "WT" "KO" \
	--whatToShow "plot and heatmap" \
	--perGroup \
	--heatmapHeight 10 \
	--heatmapWidth 5 \
	--colorMap viridis \
	--plotColors notacolor alsonotacolor
usage: plotHeatmap -m matrix.gz
help: plotHeatmap -h / plotHeatmap --help
plotHeatmap: error: argument --plotColors: 'notacolor' is not a valid matplotlib color. Use a named color (e.g. 'red') or a hex value (e.g. '#ff0000').