Baseline Offset is dependent on Number of Spin Systems

[mgiammar]

Steps to reproduce:

1. Create a new document
2. Add BlochDecaySpectrum for 1H
3. Go to Methods tab and add Constant Baseline Offset of 1 under Signal Processing
4. Go to Spin Systems tab
5. Add new 1H spin system
6. Observe baseline on the spectrum
7. Repeat from step 5 for desired number of spin systems

Expected behavior:
The spectrum always shows a baseline at 1

Observed behavior:
The spectrum baseline is dependent on the number of spin systems. For n>1 spin systems and a defined baseline offset of b the observed offset is n*b

[mgiammar]

The issue stems from these lines of code

mrsimulator-app/app/sims/__init__.py

Lines 172 to 174 in 933f373

	if decompose == "none":
	for mth in sim.methods:
	mth.simulation = add_csdm_dvs(mth.simulation)

The individual spin systems have the signal processor operations applied before being combined into a spectrum. When each of n spin systems each have a baseline offset of b applied then adding them together will result in a spectrum baseline offset of n*b

[mgiammar]

Root of issue lies deeper within mrsimulator app. The fix in #21 is temporary. Further discussion on how to proceed is necessary. Also see #32