add unittest.js and unittest-files folder

Initial commit to get the basis for adding tests.
Files under unittest-files were copied from LiveDevelopment-test-files
migrate JS Editing test

not passing but main structure and shared dependencies added.
stay in the same browser tab when switching html docs in editor.
Merge pull request #11 from sebaslv/tests

Basis for start creating/migrating tests
cleaned up some console.log calls
Merge remote-tracking branch 'shahabl/feature/singletab2'