Bind an entity reference instead of an rvalue

Summary

Whenever a local-function is bound to an element, the element should be passed as an lvalue and not an rvalue. The bind(Element const&) function takes just a const& so we don't know what we get. This MR, fixes the binding in the intersections and stores the bound element in some local-functions instead of just creating a pointer to the argument.

added 2 commits

• afcfc84a - Replace shared_ptr by optional
• 5b4ce759 - Do not bind an element if a LocalView is already bound to an element

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added 1 commit

• 76119e76 - Add OptionalNoCopy to allow copy of optional<Geometry> with a non-copyable Geometry

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added 1 commit

• cac1ec07 - Store GridFunction by value or reference wrapper

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added 1 commit

• 45632ea7 - Add ResolveRef utilities from dune-functions

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added 1 commit

• 3e6c5726 - Cleanup of several parts of the code

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resolved all threads

added 1 commit

• cfde9e50 - Fix the naming of normals in NormalGridViewFunction

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mentioned in commit 13c6fc3a

merged