[Info Q3] reformulation issue
Fix : #101 info2 Q3
Displacement current : clarification
Wave equation (general introduction) and details

+ General expression of wave equation and propagation equations.
+ Solution of wave equation in particular cases.
+ Restructure EM waves : general properties and (after) derivation of
wave equation from Maxwell's equations.
+ Other details
Remove trailing spaces
Merge pull request #104 from alegat/master

[Info Q3] reformulation issue
Rephrase last ligne #104 - info q3
Merge pull request #108 from jdewasseige/master

correction in math q3 + add package in elec q1 + spelling
Rename PNG -> png #107 - physique q3
Merge pull request #109 from cassiersg/update_phy3

Update phy3
Add author - physique q3
Correction matlab example
Merge pull request #110 from anpar/methodnum

Correction matlab example
Ajout rappels, branches, coupures, etc
Remove useless packages
Ajout effet photo-électrique, compton, etc
Merge pull request #111 from anpar/master

q3/math - Ajout rappels, points de branchements, branches, coupures, etc
Merge pull request #112 from anpar/physique-q3

Ajout effet photo-électrique, compton, etc
ajout details pour creer une nouvelle synthese