Add parameters for using another template and/or css

[dascritch]

To simplify personnalization and creation of template, shadow-dom style and i18n, may be I should provide parameters and/or attributes to use another elements instead of prebuild templates ?

It will still be more efficient for load/ready time to have it embedded into the library.

My proposals :

• use-template : Use an already loaded template, may be with its own stylesheet
• load-template : Insert a template (from same domain)
• load-css : Insert a stylesheet in the template (from same domain)
• load-i18n : Load locales strings from a JSON file (from same domain)