Tool: added `activate`, `deactivate` and `switch_to_photo` methods to react to activate, deactivation of Tool and to switching between photos.

Profile fusion: When the results cannot be saved, show a message and provide an option to specify a different save path (Closes #224)

MeasurementViewer->vector/matrix view: added spacing between consecutive tables for better clarity (Issue #221)

removed a line deleting setting widget for a tool - it was causing a crash when reactivating the previously deactivated tool with a setting widget

fix photos ordering bugs when in `ScaleSettingWidget` + clicking `Cancel` closes the widget when in importing phase (Issues #209, #210)

delegated scale extraction in ImportDialog to ScaleSettingWidget's method + fixed crash when clicking "Assign scale value to all photos" (Closes #208)

some exception handling when downloading + included Tesseract back in the repo (not in pypi package though)