Definition of complexes

+ definition of mod and arg based on polar coordinates
+ interval for Arg : [-pi, pi[, not ]-pi, pi]
+ definition of complex exp.
Merge branch 'master' into math3
Merge pull request #2 from cassiersg/math3

Math3
Merge pull request #113 from anpar/master

Meilleures définitions argument/module
Clarifications et ajouts divers
Précision niveau d'énergie oscillateur harmonique
Merge pull request #114 from anpar/physique-q3

Clarifications et ajouts divers