Inherits object.
This is the place where to put stuff that any module may need, a kind of COMMON.
An instantiation is done in the main __init__ file using the "config" name.
Define variables that will be known from everywhere:
- INSTALLED: a dictionary whose keys are the libraries that PyNeb may need
e.g. 'plt' for matplotlib.pyplot, 'scipy' for scipy.interpolate. and whose values
are Boolean
- Datafile: a dictionary holding the HI atom, which can be used intensively in Atom.getIonAbundance
- pypic_path: This is only set when needed (basically by getEmisGridDict).
The default value for the pypic_path parameter of getEmisGridDict().
The first try is ./.pypics: if it cannot be created, or it exists but it is not writable,
/tmp/pypics is tried; if it cannot be created, or it exists but it is not writable, the path
is set to None and a pypic_path value shall be provided to getEmisGridDict().
Parameters: none