This is done mainly to avoid problems with trailing whitespace in the
generated Python code as this provokes pep8 problems, but is also, arguably,
more logical, as if a command which is on its own on a line is ignored, we
shouldn't leave any whitespace neither (and perhaps should even suppress the
line entirely, in fact).
This is unnecessary and inconsistent with "builtin" case in which the
docstrings are not indented in the generated C++ code, thus making it
impossible to write tests working in both cases.
Most of the changes in this commit simply remove the extra whitespace from the
expected values in the tests.
Add %feature("doxygen:ignore:<command>") implementation, documentation and
test case.
This feature allows to use custom tags in C++ Doxygen comments for
C++-specific things that don't make sense in the context of the target
language and also allows to insert contents specific to the target language in
the C++ comments using (different) custom commands, which is very useful in
practice to explain the particularities of the API wrappers.
