geometric mean implementation

[prabhathc]

• src/lib/index.js @prabhathc

• src/lib/stats.js @prabhathc

• src/plots/cartesian/layout_attributes/js @prabhathc

• src/plots/plots.js

• test/jasmine/tests/calcdata_test.js @acxz (sorta? tests stopped working)

• test/jasmine/tests/lib_test.js @acxz
  feature(geomean): add geomean function plotly/plotly.js#6223

• docs? https://github.com/prabhathc/graphing-library-docs/tree/feature/geomean
  Add Geomean documentation plotly/graphing-library-docs#182

Do we need to add doc changes to all client languages? Big question