contenerize with `` variable names in notebook

[yannrichet]

rsession/src/main/java/org/math/R/R2jsSession.java

Line 2790 in 2ad82f3

note_code(varname + " <- " + (data == null ? "list()" : toRcode(data)));

should use toto <- d...
so any name instead of tot is valid 'inclufing special chars, ...)

Also todo for other Rsession impl.