pubs: Fellwalker - we do not compare FellWalker with other types of algorithms

The referee wanted some discussion of other algorithms.
pubs: Fellwalker - referee sees little difference between fig.s 5 and 6
pubs: FellWalker - referee wants "total data sum" explained
pubs: FellWalker - referee wants "STC-S" explained.
pub: FellWalker -  Gaussclumps would do better with test gaussians

Referee says "In the test case of Gaussian mixtures (Figs. 7, 8), the
obvious method to compare FellWalker to is a Gaussian mixture model.
I am not asking for this to be implemented and tested, but I suggest
the author speculate on the advantages and disadvantages of FellWalker
compared to that. One obvious benefit of FellWalker is that it assumes
no fixed shape, although a particular algorithm may perform better for
Gaussian mixtures."
pub: FellWalker - differentiate more clear between different sets of test data

The referee says "Although in Sect. 3.1, the text says that all the
Gaussian sources have equal amplitude, that does not appear to be so,
by eye. Is that because of an improbable number of overlaps, does my
eye deceive me, or is the text wrong? Fig. 11, on the other hand,
does seem to have a set of equal, superimposed Gaussians."

In fact he was mis-interpreting the scope of the statement about
constant peak values.
pubs: FellWalker - clarify the meaning of the gain value.

The referee found the gain value confusing.