Add overlay message popup
Merge pull request #575 from nicolas-f/feature/overlay_message

Add overlay message popup
Fix end user messages and size of the workspace folder
FIX  html tags
Fix html tags and replace toc by Toc
Merge pull request #577 from ebocher/fix/messagesforEndUser

This PR adds some new messages for the end user when it manages a style.
It fixes also the size of the workspace window to 200px.