viewer additions

[falon3]

As per meeting:

1st and 2nd lines should have consistently different select shapes(for 1st and 2nd)
different sessions will be a different color scheme

[falon3]

this is mostly only relevant if more than one session can be viewed at same time... but 1st and second lines should be different shapes

[falon3]

Update to do just line 1 red, line 2 blue sort of thing. only view one session at a time