ensure valid BPMN 2.0 parent when
* creating/moving data store
* removing participant
* turning process into collaboration
* turning collaboration into process
Closes#483
* use ES6 import / export
* UTILS: export individual utilities
* TESTS: localize TestHelper includes
BREAKING CHANGE:
* all utilities export independent functions
* library sources got ported to ES6. You must now use
a ES module bundler such as Browserify + babelify or
Webpack to consume this library (or parts of it).