refactor(layout): switch to flex layout
refactor(ui): change to responsive controls
chore(css): remove unused code
refactor(dataviz): move dataviz into separate file

* map-app.js: map dataviz
* flow-app.js: sankey dataviz
feat(sankey): add CSS style
refactor(layout): switch to flex layout and reorganize
chore(git): ignore ecv-ijba symlink and sankey/ directory
chore(css): clean unused code
feat(ui,js): add methods to update counters
refactor(sankey,map): create shared methods to highlight/show information
docs(image): add new preview image with sankey
chore(package): add project/dev dependencies