In reservoir state method, use the deepest well to choose the matrix bandwidth.

We use a banded matrix in the reservoir state method to accelerate the
linear solve. The halfbandwidth of this matrix is chosen by neglecting
P(E,E') values below a certain threshold. It is important to choose the
deepest isomer well for this, as it gives the largest halfbandwidth and
therefore the safest banded matrix.

I noticed this issue in a PES where I had a very shallow adduct as the
first isomer well. Since the previous implementation used the first isomer
only to choose the halfbandwith, it was choosing a value that was far too
small for the other isomer well.
Implemented preliminary version of CSE lumping algorithm.

The lumping algorithm applies when you are deficient by at least one
reaction timescale due to blending into the collision timescales. It
eliminates one or more isomer wells from consideration and returns the
subset of the k(T,P) values for the remaining configurations. This might
be useful for investigations of individual networks in detail.

The priority of lumping is indicated with the lumpingOrder parameter;
probably you want to lump the shallowest isomer wells first most of the
time. (Think pseudo-steady state approximation, not rapid equilibrium
approximation.) If the lumping order is not specified, or if the list is
too short to account for all of the missing eigenmodes, the CSE method
fails as before.

I don't know if there is a good way to "unlump" to fill in the missing
k(T,P) values.