Generate platform-specific installers automatically

[joffrey-bion]

We should support Windows .msi and .exe, MacOSX .app, and Linux .deb for starters.

[joffrey-bion]

• The Linux package could be handled by a Travis build (on linux).
• The Mac OS package should be possible also directly with Travis by setting up a build on a mac docker.
• Windows installers are currently supported by building locally on my windows machine:
  • .exe installer handled by Inno Setup
  • .msi installer handled by Wix Toolset

The windows installers could later on be automated by Travis using wine to access these 2 softwares: https://blog.heckel.xyz/2014/05/29/gradle-create-windows-installers-debian-packages-manage-a-ppa-and-optional-sub-projects/

[joffrey-bion]

One problem with exe installer file creation with InnoSetup. I could only find the source of the problem by adding the --debug flag.