Work package version 5.2.0

[fr43nk]

Fix some issues in the current version

• Add a command "diff with previous" to the context menu in the editor.
• allow Version Tree with hijacked files
• fix Editor title buttons appearance. Currently an additional click in the document is needed to show some buttons
• allow usage of .ccignore files for filtering of view private files (allow usage of .ccignore files for filtering of view private files #188)
• allow relative paths and ${workspaceFolder} additionally as a search path for view private and hijacked files
• fix "edit config spec" feature.