A big thank you to Bertrand who showed us that we hid away a tremendously useful zip/unzip feature in the project management tools: The possibility to upload multiple files and folders to a project in one step.
This is how the story goes: Zip your files, upload to project and unzip:
A. Zip your files/folders and then upload:
B. Right click the zip file and choose "Extract here"
C. Another tip: Mark files or folders for translation in one step
Select all files and folders, right click and choose "Mark for online translation":
Selecting multiple files or folders works like in Windows: Click with the Shift or Ctrl key pressed or use Ctrl-A to select all files.
The context menu gives access to some other useful features: For example the possibility to download files as a zip archive.