This commit reduces the number of test runner workers for Jest tests
from 10 to 8. This will use less memory and hopefully avoid Circle CI
4GB memory limit test failures. It also fixes some tests that have
nested `it` clauses. This doesn't run correctly on older versions of
Jest and will fail fast on newer versions of Jest.

Fixes #6790

* virtualize select content

* clean up example

* show examples

* use vendor bundle

* add command to generate webpack stats

Our docker containers currently building with the Alphine system
nodejs package (6.7.0) so this lowers our minimum version to that in
packages.json and changes the circle config to use that same version

Yarn 1.0.0 has been released and it doesn't appear to work with the
version of node we current have configured (4.4.7). Bumping to 8.4.0
to get the build green again.

Yarn 1.0.0 has been released and it doesn't appear to work with the
version of node we current have configured (4.4.7). Bumping to 8.4.0
to get the build green again.

* Ask from user before quitting when using test-integrated-watch

* Add helpful logging to the runner script, refactor file hierarchy

* Add a way to dispatch browser events in tests

* Update test command names and rewrite the frontend testing docs

* Fix test failures

* Add :largest-contributors to comparison, bug fixes, refactoring

* Add valid-pairs and field endpoints to comparisons

* Dampen field difference weight in contribution assesment

* fix nice-bins for empty histogram

* fix for nice-bins for histogram with only 1 value

* Change comparison field zoom in. Rename largest-contributor to top-contributor

* fix halfassed rename

* refactor + new components

* use true multiseries

* cleanup

* include constituents in card

* add dataset to card return

* card wip

* growth rate

* check for values

* lint

* cardify all series features. Unpack linear regression

* add linear regression

* use percentages

* flip order

* add growth series description

* add additional info

* fix layout

* layout tweaks

* add action in qb

* show growth series as a %

* xray segment action

* flow

* Support all time breakdowns, fix filtering bug

* make linter happy

* more robust test

* Add conditional descriptions for growth-series. Update tests.

* add periodicity to cards

* Update for updated distance measure

* Removed updates to comparison as they should not be part of PR

* Correct chi^2 distance

* fix headings

* fix flow

* disable flow for action

* use beaker for xray actions

* move specs to proper test directory

* Fix round-to-month when crossing year

* add key

* Add smoke tests for table xray and segment xray pages

* Correctly handle unixtimestamps encoded as bigints

* Add test cases for question xray page and segment xray query builder action

* Test also timeseries question action widget action

* Fix lint errors for xray tests

* Fix Histogram element passing data in invalid format to Visualization

* Fix integration tests for xrays

* Make xrays urls in services.js consistent with other urls

* fix periodicty reweighing

* cleanup

* spacing

* cleanup

* fix failing tests

* Remove duplicated code from binning

* remove PKs from constituents

* Add rolling window XoX growth. Update time series decomposition

* Add descriptions for new time series features

* fix comparison

* The big rename

* add xray namespace and rename

* match updated endpoints

* fix threading

* Apparently we don't have to cast *id

* Fix field comparison

* api change: constituents are now keyd

* wip

* Unify shape of features for empty datastets with normal features

* Refactor

* use new structure

* hardcode order

* segment/segment

* comparison button

* histogram colors

* more layout tweaks

* sort by distance

* compare icon

* Refactor, generalize metadata/db-id

* more layout

* add cost to comparisons

* First round of tests, some bug fixes

* comment out currently unsed spec to make linter happy

* add cost to comparisons

* add titles

* use terms for difference

* remove uniqueness

* comparison items hover

* fix segment comparison link

* fix field sort by distance

* lint

* fix button

* fix comparison table borders

* switch to react-dom/test-utils

* remove dependency

* add image files and get new text in there

* modal content + refactor

* update illustrations and remove redundant one

* add tests

* add images

* button text tweaks

* padding