added Piecewise
corrected bug in table.html() when no header and no titles
added linear_repartition and test
utilities for unit tests (using nose)
imports Goulib.tests instead of nose
+.ipynb_checkpoints
Color.repr returns cosntructor-like string
added Expr._repr_latex_ (sort of...)
import abc #is now lazy
stupid error corrected in cgiprint
updated
comment typo
 [a,b[ + [b,c[ now returns [a,c[
added linear_repartition
group can now be init'ed with data=[Entities]