#742 SBE course: add modules 1.3 - 4 + course files + some other improvements

• End-user visible changes:
  • Mark the SBE course as work in progress.
  • Small fixes for SBE course Modules 1.2 + 1.3.
  • Add SBE Course Modules 1.3 - 4.
  • Add SBE course files project and wizard. Includes course files for Modules 1-4. Allow importing SBE course files from the Welcome screen.
• Other changes:
  • Improve SBE course image build script: allow building only some images, rather than always all of them.

The idea is to contribute this first version of the content, without a thorough review of the content. The content will, in parallel (not in this merge request) be reviewed, to come to a plan for a next improvement pass over the content.

Addresses #742 (closed)