Msys build

Context

This merge request brings a new build on Windows using MSYS2.

Major changes

• MSYS2 build is now supported for Windows platforms

Minor changes

• Apache 2.0 license has been added to each file (more or less)
• [Flow] Transpiration boundary condition and dummy coupler have been added to prepare Amaury's work on viscous/inviscid coupling

Tests

• Passed on ubuntu 18.04, debian (gaston)

CODEOWNERS

@@ -4,17 +4,17 @@
 # These owners will be the default owners for everything in
 # the repo. Unless a later match takes precedence, they
 # will be requested for review when someone opens a pull request.
-*       @rboman
+*       @R.Boman
 
 # These owners own a directory and nested subdirectories
-/fdtd/ @rboman
+/fdtd/ @R.Boman
 /flow/ @acrovato
-/heat/ @rboman
-/mirrors/ @kliegeois
-/mrstlnos/ @kliegeois
-/sph/ @rboman
-/tlnos/ @rboman
-/waves/ @rboman
+/heat/ @R.Boman
+/mirrors/ @Kim.Liegeois
+/mrstlnos/ @Kim.Liegeois
+/sph/ @R.Boman
+/tlnos/ @R.Boman
+/waves/ @R.Boman
 
 # You can also use email addresses if you prefer. They'll be
 # used to look up users just like we do for commit author