In pretofunc module : Add the implementation of the closure function and
the interior
function. Import the rel function from the module spaces. 

In spaces module : create a function for the binaries relations between
entities in a set. The function is not yet defined
add the examples package for constructing networks. We begin with the
examples 
of a pairwise network of tweets. the edges are created when a user cite
another 
in the begining of his tweet by using '@' character. 

We used the library networkx for the construction and the analysis of
networks. 

We added the package ml for all the machine learning algorithms that we
are going 
to use for the analysis of multi-layers networks. 

We added the function interior in the module funcpreto
Merge remote-tracking branch 'origin/master'