* add simple error message helper
* port all label name pickers to use the new LabelInput component
* use pure components where possible
* cleanup
* more cleanup
* lint
* change new label prompt
* load annotations individually
* fix type check to be more general
* update node CI version from 10 to 12
* node 11
* debug print node version
* travis node version to latest
* try nvm
* remove extraneous node_js statement
* remove node version debugging printf
* incrementally load all annotations and layout
* process annotations and layout as they are loaded
* fix tests
* sort categories incrementally
* incrementally build category view summary; add category loading spinner
* add spinner to continuous metadata
* configure undoable reducer
* incremental crossfilter creation
* improve busy layout
* more layout cleanup
* correctly reconcile categories in schema
* refine layout of lsb spinners
* more spinner layout work
* more spinner layout
* always load layout before obs annotations
* add own range() function
* lodash cleanup
* remove redundant fill range implementations
* remove use of _.get
* sync test babel config with build
* update tests to match new range implementation
* immutable crossfilter
* first cut at reducer refactor with cascade model
* add initial redo/undo implementation
* small optimization
* integrate expression with history
* add tests for new reducers and fix a couple of small initialization bugs
* treat tiny lasso selections as a clear
* better function name for clarity
* fix undo for differential expression
* remove logging
* fix regression due to bad merge
* cleanup and comments for clarity
* improve undoable configuration for flexibility
* fix stale comments
* remove debugging code from production build
* rename categoricalSelectionState
* rename file
* improve comments