MeshTools: fix Clang warning about implicit cast changing a value.

Magnum/MeshTools/RemoveDuplicates.h:373:30: Requested here: Implicit
conversion from 'std::size_t' (aka 'unsigned long') to 'float' changes
value from 18446744073709551615 to 18446744073709551616
[-Wimplicit-int-float-conversion].

Not that it would really matter at this scale, but thanks anyway.

src/Magnum/MeshTools/RemoveDuplicates.h

@@ -232,7 +232,7 @@ template<class IndexType, class Vector> std::size_t removeDuplicatesFuzzyIndexed
 
     /* Make epsilon so large that std::size_t can index all vectors inside the
        bounds. */
-    epsilon = Math::max(epsilon, typename Vector::Type((minmax.second-minmax.first).max()/~std::size_t{}));
+    epsilon = Math::max(epsilon, typename Vector::Type((minmax.second-minmax.first).max()/static_cast<typename Vector::Type>(~std::size_t{})));
 
     /* Table containing original vector index for each discretized vector.
        Reserving more buckets than necessary (i.e. as if each vector was