Add a colormap to a Next Generation Clustered Heat Map (NGCHM) and return the extended CHM. Duplicate colormaps will be silently dropped.
Usage
chmAddColormap(chm, colormap)
# S4 method for class 'ngchm,ngchmColormap'
chmAddColormap(chm, colormap)
Details
Note that it is not necessary to explicitly add colormaps included with data layers or classification bars. These will be included automatically. Explicitly using this function is only required in order to add additional predefined, but unused colormaps to the NGCHM.