Merge branch 'cluster' into 'master'

build/README.md

doc/src/config.dox

src/README.md

src/cluster/Makefile

src/cluster/clu.f

src/cluster/cluster.cpp

src/cluster/np_cluster.cpp

src/include/Commons.h

src/include/Configuration.h

src/include/clu_subs.h

src/include/sph_subs.h

src/libnptm/Commons.cpp

src/libnptm/Configuration.cpp

src/scripts/README.md

src/scripts/pycompare.py

src/sphere/Makefile

src/sphere/edfb.cpp

src/sphere/np_sphere.cpp

src/sphere/sphere.cpp