[xy-chart] add <StackedAreaSeries /> and onClick support to all series

[williaster]

🏆 Enhancements

• [xy-chart] adds <StackedAreaSeries /> and example
• [xy-chart] adds onClick support to all series and voronoi
• [xy-chart] removes previously-required label prop from series
• [demo] adds <LinkedXYCharts /> example with custom click handling and mouse overs
• [demo] adds disableMouseEvents prop to all series
• removes enumeration of @data-ui packages in readmes

🐛 Bug Fix

• fixes a bug for bar offsets

🏠 Internal

• [shared] bumps @vx/tooltip to 0.0.147 for smarter tooltips

[coveralls]

Coverage increased (+0.9%) to 84.137% when pulling 488e821 on chris--series-onclick into de7642e on master.

[coveralls]

Coverage increased (+0.9%) to 84.137% when pulling 488e821 on chris--series-onclick into de7642e on master.

[coveralls]

Coverage increased (+0.9%) to 84.137% when pulling 488e821 on chris--series-onclick into de7642e on master.

[coveralls]

Coverage increased (+0.9%) to 84.137% when pulling 488e821 on chris--series-onclick into de7642e on master.

[coveralls]

Coverage increased (+1.0%) to 84.18% when pulling 08dfaeb on chris--series-onclick into de7642e on master.

[coveralls]

Coverage increased (+1.0%) to 84.18% when pulling 2ff57f1 on chris--series-onclick into de7642e on master.