Modularising rash.js for being used in RAJE

[essepuntato]

The script "rash.js" must be modularised in order to call specific visualisation functions independently from the others in external applications (such as RAJE).

[gspinaci]

Update addHeaderHTML in order to reuse it from different container.

I.E. normally it's called from the html tag, but if an override is needed (RAJE with TinyMCE) it can be called from #raje_root. In this case, RAJE will update the existing header wrapped in #raje_root (without adding a new one).