:bug: Fix autocompletion with multiple selections

Fix saschagehlich/autocomplete-plus#57
:green_heart: Fix broken positioning tests

Despite setting the height in lines of the editor view, its
`outerHeight` always returned 0.
Merge pull request #101 from abe33/feature/multiple-selections-support

Feature multiple selections support
Flow out to contraints
Merge pull request #113 from blakeembrey/fix-popup-menu

Flow out to contraints