Adds bugfix, translation & examples

- corrects an error in the save script that could result in destroying
UTF-8 multibyte characters (thanks, Matthias R.!)

- translates all interface messages and comments to English

- adds directory "testtexts" with sample files randomly picked from
the German Wikipedia and a demo text file with multibyte characters
for testing the bugfix.
Updates Readme.md
Merge branch 'master' of https://github.com/wortwart/node.js-editor-demo