* 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).
This adds immediate feedback when creating and moving boundary events.
* During move, boundary events are snapped, if attachment is allowed
* Boundary events snap to their siblings and not to elements inside
the host
Closes#320