Need to allow single tag for different modes in a single set

At this point, the flow is entirely reactive, starting from the file inputs.

But, plotting does not work for MS2 chrom and spec

In the last couple of commits, the application has become much more
reactive. I have focused on throwing out as many as possible important
observers in favour of render/reactive environments.

As a consequence, the application is much more responsive to change
and updates properly almost all the time.