Release version 0.0.42 beta - most recent changes from @sebsauvage

Before making/merging any changes to the master branch of the new Shaarli organization, I would suggest we release the latest v0.0.42beta version, to contain all the changes up until the creation of the organization.

That version represents the state of @sebsauvage's master branch at the moment the organization was created, and is thus the last version as fully controlled by Seb.

If you agree, please merge this pull request.
I have also tagged versions 0.0.40beta, 0.0.41beta and 0.0.42beta in this branch, in order to have versions properly tagged. Not sure if tags are migrated with the pull request, otherwise we can add the tags later. For reference, these are the commits associated with each versions:
- 0.0.40beta: 450342737ced8ef2864b4f83a4107a7fafcc4add
- 0.0.41beta: 310f3ca0079a03eaa627f94b65486e4547aeb3d9
- 0.0.42beta: 4ade7393a33e0ae3b40bb6a4dc8e051b0ed04169