Add Antoine Paris to authors - math q3
Second order equations : initial conditions

Precisions and corrections about initial conditions for second order
equations (wave equation and diffusion equation with infinite domain).
Diffusion equation: solve with integral of Dirac
Small corrections
Address comments of pull request
Merge branch 'master' of github.com:Gp2mv3/Syntheses
Merge pull request #106 from cassiersg/math3

Math3
Merge branch 'master' of github.com:Gp2mv3/Syntheses
Remove trailing spaces - math q3
Add Gaetan Cassiers to authors - math q3