Merge branch 'master' into moar_rails_cruft

docs/developers-guide.md

frontend/src/metabase/components/AddButton.jsx

frontend/src/metabase/components/AdminAwareEmptyState.jsx

frontend/src/metabase/components/ConstrainToScreen.jsx

frontend/src/metabase/components/DeleteQuestionModal.jsx

frontend/src/metabase/components/Sidebar.jsx

frontend/src/metabase/css/core/rounded.css

frontend/src/metabase/css/query_builder.css

...end/src/metabase/new_query/containers/NewQueryOptions.jsx

frontend/src/metabase/new_query/new_query.js

frontend/src/metabase/new_query/selectors.js

...rc/metabase/query_builder/components/CardFiltersWidget.js

frontend/src/metabase/reference/databases/DatabaseList.jsx

...rc/metabase/reference/databases/NoDatabasesEmptyState.jsx

frontend/src/metabase/reference/metrics/MetricList.jsx

frontend/src/metabase/reference/segments/SegmentList.jsx

frontend/src/metabase/routes.jsx

frontend/src/metabase/xray/SimpleStat.jsx

...tend/src/metabase/xray/components/XrayFieldComparison.jsx

frontend/test/__runner__/run_integrated_tests.js