The Color class now keeps track of RGB and HSV in preparation of better HSV use,
e.g. HSV based gradients. The interface has been extended, and parts of the old
interface have been deprecated (by means of in-source comments, not yet as
messages when using it); this applies to both C++ and Python. Instead of
gfx.Color() use the factory functions gfx.RGB(r,g,b), gfx.RGBA(r,g,b,a),
gfx.HSV(h,s,v) and gfx.HSVA(h,s,v,a). See also gfx/color.hh for in-source doc

naccess does not like dots in path names. Some temporary directories
contain dots, which causes naccess to fail. We now provide a scratch_dir
option, which allows to specify a temporary directory.

Also, allow to set the maximal number of atoms supported by naccess.

added cmake option to set hidden visibility for gcc compiles; fixed several missing visibility declarations

Fixes BZDNG-385

installation docu: mentioning fortran as requirement for TMTOOLS; fixing typos; fixing link to compoundlib docu

Mainly Marco's work