Remove some overhead from line_scatter
Remove some overhead from line_scatter

Previously rpacket_set_next_line_id() was called at the beginning of the
function and later get_next_line_id() - 1 was used to get the current
id. This was changed and set_next_line_id() is now called at the right
position.

orbitfold/tardis,kaushik94/tardis,kaushik94/tardis,kaushik94/tardis,orbitfold/tardis,kaushik94/tardis,orbitfold/tardis,orbitfold/tardis,Tobychev/tardis,Tobychev/tardis,Tobychev/tardis