Doxygen: changed output dir to html, BORNAGAIN_PYTHON definition added, @brief propagated to class method list

Redmine: #1858
in Material class hierarchy

A few more virtual->final, protected->private. Start manual revision (reactivate outcommented sections).

11ify IShape2D and children (intended to enable automatic Python export, which however is impossible because these classes are not IParameterized).

Top-level routines moved from Fit/Suite to Core/Fitting.
Some base classes and utilities moved from Core to Fit/Utils. This requires more thought.

Since RealParameterWrapper now knows its name, ParameterPool needs no longer to use a map: converted to vector, just for conciseness.

new file Fit/FitKernel/AlgorithmNames.h so that Fit no longer depends on Core/Basics/BornAgainNamespace.h

the remaining Doxyfiles write to subdirectories html/std, long, dirgraphs