#190 Various renaming issues

[Ulf Lorenz]

What and Why

With the new functionality of [#144], several terms have gotten new or more precise meanings. to avoid identical names for different concepts, the class names should be adjusted. Since this is a breaking change, it should be done as early as possible.

• Fix capitalization. For example, we use dvrToFbr(), but FFTTransformation.
• In the doxygen documentation, always explicitly use the namespace in cross-references. It is introduced in the beginning, I think people can handle that.
• The name "transformation" is used for two different concept: Transformations between representations (fine) and modifications of operators. The latter has to be renamed.
• With the transformations, we introduced representation as a concept with two ingredients: a grid and a meaning of the coefficients. We only track the former, but not the latter. This clashes with the name of the Representation class, which only describes the grid part. Suggestion: Rename all simple grids to ...Grid1D, rename Representation to GridND. Note that all references also need to change then (Python argument names, function names, BadRepresentationException, ...)

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renamed simple grids to DegreeOfFreedom for better distinguishability; did not use camel case for IOException and NIPFactory, because both should be replaced by further refactorings.