editor: fix save alternative problem.

[zannkukai]

Due the previous changes, the dynamic save alternatives behavior was
broke : all alternatives call the same function instead of to use the
function define for each alternative. This commit fixes this problem.

This commit also introduces the "ngVar" directive to assign value to an
angular variable.

Co-authored-by: Renaud Michotte renaud.michotte@gmail.com

How to test?

• Try to save a document as a new template.
• After click on "save as template" alternative, the popup should appear.
• Enter the template name you want to use and click on 'save' button.

Code review check list

• Commit message template compliance.
• Commit message without typos.
• File names.
• Functions names.
• Functions docstrings.
• Unnecessary commited files?
• Extracted translations?