Possibility to share same note with multiple charts

Note functionality has been updated to support assignment of notes to multiple charts and global notes.

eea.googlecharts is now dependent on collective.js.underscore, which brings in the underscore.js library that offers several useful utility functions and a templating system that is used to move some of the string-based templates to an external file, from where they can be more easly managed and reused.

http://taskman.eionet.europa.eu/issues/19048