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)

changed the title of the app to 'MAPHIS', the title includes the location of project and the name of the currently viewed image

Rename 'arthropod_describer' to 'maphis'

See merge request xmraz3/arthropod_describer_py!3

convert 'arthropod_describer'-specific keys to 'maphis'-specific keys to be compatible with projects created before the name change

multi-page tiff files: work only with the first page (just for now) + display a warning when a multi-page tiff file is present in the import queue + solved the crash when opening the scale setting widget for a multi-page tiff image (Closes #202)

loading of measurement configuration implemented (no loading of computation settings yet) (Issue #192)