Node-RED 0.19.x allows to customize the icon of each node. It seems to search for all available icons in the "traditional" nodes as well as in the "node-red-contrib" nodes ... but it seems to retrieve only PNG files and ignore SVG files ... am I right ?
Also, is there a way, to provide a custom icon without it being an icon used in another node ?
currently it only lists .png and .gif files - missing off .svg was more an oversight rather than intentional restriction. Will sort that out for the next maintenance release.
There is not currently a way to include your own icons outside of a node module. We are looking at enabling the use of the Font-Awesome (4.7) icon set - and potentially other web fonts - but that won't be until the next milestone release.