I propose to refactor the code in VolumeFromSTL in order to improve code readability and allow @francoisdh to have a look at the code.
In the src directory:

• Move all the applications *_main.cpp in an src/applications directory;
• Split the volumefromstl.hpp in the include directory into as many files as there are classes.
• Split the volumefromstl.cpp file which contains all the classes implementation into as many files as there are classes in it.
• Create a src/libraries directory where we put all the source files that are part of the angiotk_meshing_volumefromstl library.
• Ensure that everything builds correctly with CMake

What do you think about it ? @prudhomm @vincentchabannes @francoisdh