Set the starting position of the MSA

[homonecloco]

I would like to be able to initialise a position from where to show the MSA, but still be able to scroll backwards (something like

var msa = new biojs.vis.msa.msa({el: div_obj, seqs: seqs, start_pos=50})

[wilzbach]

you can use it like this:

msa({el: div_obj, seqs: seqs})
msa.g.zoomer.setLeftOffset(10)
``