Implement support for manual index transformations

Add TransformedIndexPreBasis and demonstrate its usage.

This pre-basis transforms the global multi-indices of a wrapped pre-basis. This functionality can be helpful to create indexing schemes which cannot be constructed using the index merging strategies of PowerPreBasis and CompositePreBasis.

While the implementation works as desired. This is marked WIP, because I'm neither convinced by the design of interface and implementation, nor is this suitably tested and documented.

For an example have a look at patch for stokes-taylorhood.cc which is included. This transforms one indexing scheme for the Taylor-Hood basis into another. To keep the example program as is otherwise, the target indexing scheme coincides with the one in the unpatched example.

added 2 commits

• 26ce3661 - Add TransformedIndexPreBasis
• c0a1d492 - Use index transformation for demonstration

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While I'm not sure if the current interface will persist, I'm aware of several people that might be interested in using this functionality.

To be able to try this out and get feedback without making this public to any user I moved the interfaces to a new namespace Dune::Functions::Experimental and plan to merge this soon. Whoever wants to use this should follow the dune-functions development to keep track of potential breaking changes (or be on my private list of known tester whom I will notify).

added 361 commits

• c0a1d492...d1bc921b - 359 commits from branch master
• 66f7ca82 - Add TransformedIndexPreBasis
• 808d85f4 - Use index transformation for demonstration

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added 2 commits

• 55c7a1f5 - [doc] Minor doxygen improvement
• 4df9eb6e - [cleanup] Remove backward compatibility for experimental code

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added 44 commits

• 4df9eb6e...72dd909f - 41 commits from branch master
• 029e9f9b - Add TransformedIndexPreBasis
• fd2e1dc6 - [doc] Minor doxygen improvement
• 6453d0ba - Use index transformation for demonstration

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added 2 commits

• 8bb1b2df - Remove <TP>
• 5806f08a - Use index transformation for demonstration

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mentioned in issue #31 (closed)

mentioned in merge request !216 (closed)

mentioned in issue #47 (closed)

mentioned in issue #54 (closed)

mentioned in issue #53 (closed)

added 75 commits

• 5806f08a...9ef325e5 - 71 commits from branch master
• ac75b051 - Add TransformedIndexPreBasis
• 8d8f69a4 - [doc] Minor doxygen improvement
• fce54980 - Remove <TP>
• 0bb123ae - Use index transformation for demonstration

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I rebased on master and force pushed. This allows to test the branch against the current master of the core modules.

added 57 commits

• 0bb123ae...a7318c66 - 56 commits from branch master
• 3620ef77 - Add TransformedIndexPreBasis

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unmarked as a Work In Progress

merged

mentioned in commit 50f7323c