add legend icons and coloramp

frontend/package-lock.json

frontend/package.json

frontend/src/Legend.vue

frontend/src/MapProperties.ts

frontend/src/StationChartPopup.vue

frontend/src/StationLayer.ts

frontend/src/WeatherMap.vue

node_modules/.package-lock.json

node_modules/colormap/.travis.yml

node_modules/colormap/README.md

node_modules/colormap/colorScale.js

node_modules/colormap/colormaps.png

node_modules/colormap/example.js

node_modules/colormap/index.js

node_modules/colormap/license.md

node_modules/colormap/night.jpg

node_modules/colormap/package.json

node_modules/colormap/res/draw.js

node_modules/colormap/res/res/CDOM.js

node_modules/colormap/res/res/PAR.js