[worksheet] when the magnification is active on the workshseet

Description

Multiple fixes for the magnification window in Worksheet and Data Extractor:

• don't draw it during the export paint (export to files, export to pixmap for the worksheet preview)
• don't print the magnification window
• hide the magnification window if the user selects the action "no magnification" directly, don't wait until the next move event
• properly update the content of the magnification window when zooming with the mouse wheel at the same time (zoom in the worksheet or zoom in the plot area under the cursor)
• directly update the content of the magnification window when new worksheet is being changed (new objects added to the plot via shortcuts, etc.).

Conformity

• Changelog entry
• Unit tests
• Update INSTALL
• Downport
• Fixes:

When external dependencies are removed

• Reporting to ...