sortConcepts: Improve numerical sorting

[nichtich]

Current numerical sorting works by reading notations as numbers. This does not work for notations build of letters and numbers such as https://bartoc.org/en/node/20406/?uri=http%3A%2F%2Furi.gbv.de%2Fterminology%2Fbrunfels%2FMedica#content

Better replace by an algorithm that splits notations into parts of type number (0-9), letters (a-zA-Z), other (everything else) and use these elements for sorting. Example:

• A.23-09a => ["A", ".", "23", "-", "09", "a"]
• A.1-11b => ["A", ".", "1", "-", "11", "b"] so 23 > 1, 11 > 09, b > a

[nichtich]

Another use case is https://bartoc.org/en/node/743#content:

• Pä 1 Allgemeines
• Pä 10 Fachdidaktik für den Pädagogikunterricht, Schulbücher
• Pä 2 ...
• ...