Changes to resource controls

[gustavdelius]

We now keep the resource spectrum constant while tuning the steady state. Here are some changes that should be made:

• The parameters should control initial_n_pp, not cc_pp.
• Change in resource in tuneParams() should update spectra immediately, both the resource spectrum and the species spectra. This change should be propagated to params_old().
• The controls should all become sliders.