[tern addon] Make it possible to pass in explicit positions
Create Tern request with optionnal pos to manage for instance tern hover. See demo at http://codemirror-java.opensagres.eu.cloudbees.net/codemirror-javascript/demo/javascript-all.html
[dialog addon] Slight modifications to openNotification
Remove callback argument, save currently open dialog in per-editor state.
[clike demo] Fix duplicate variable names for C and C++ editors
The C editor and the C++ editor have the same variable name, so the latter shadows the former. Fixed by renaming both.