Incorrect German translations of snap cusp nodes, snap smooth nodes

Version: Currect head of 0.91 branch, all OSs.

The options "snap cusp nodes" and "snap smooth nodes", which allow these kinds of nodes to snap, are incorrectly translated into German: "An spitzen Knoten einrasten" and "Einrasten an glatten Knoten" which means "snap to cusp nodes" and "snap to smooth nodes". The "an"/"to" is wrong in this case.

Btw: That these snapping-related options are directly next to each other and sometimes mean "snap something" and sometimes "snap to something" may be confusing for translators and thus may be wrong in other languages soon.

Additionally, theres a slight inconsitency of word order, punctuation and grammar in these translataion. And there's a typo in "Knotten" in one text, which must be "Knoten".

The correct translations of these strings in de.po therefore should be:

#: ../src/widgets/toolbox.cpp:1754
msgid "Snap cusp nodes, incl. rectangle corners"
msgstr "Spitze Knoten einrasten, inkl. Ecken von Rechtecken"

#: ../src/widgets/toolbox.cpp:1763
msgid "Smooth nodes"
msgstr "Glatte Knoten"

#: ../src/widgets/toolbox.cpp:1763
msgid "Snap smooth nodes, incl. quadrant points of ellipses"
msgstr "Glatte Knoten einrasten, inkl. Quadrant-Punkte von Ellipsen"