Fix Doxygen Documentation Generator

[salkinium]

This is a massive PR with a lot of small artisan changes to the documentation followed by a huge whacking of trailing whitespace removals for good measure.

This makes the modm:docs module generate the doxygen module structure by defining its groups and including the module description in it. This way the module description can be shared between the lbuild discover commands and doxygen.

To support this however, all modm modules had to be refactored to name the right @ingroup modm_module_submodule. I've also added a lot of missing classes into their respective groups.
Every lbuild module now also has a description, or at least a description title.

With this PR you can cd modm/docs; doxygen doxygen.cfg and the fully featured documentation will appear magically under modm/docs/html/ for your specific target.

cc @strongly-typed @daniel-k @mhthies @rleh @chris-durand

[salkinium]

Here are all of the modules for the F469 blink example:

[salkinium]

I'm removing the whitespace changes from this PR and putting them in a separate one, otherwise this becomes very messy.

[daniel-k]

\o/

[salkinium]

\o/

Yeah, this makes modm much more accessible for third parties. I thought you'd like this ;-P
Now we only need to address the level of detail of documentation not its complete lack of. *phew*

[salkinium]

Unfortunately, while applying whitespace removal I accidentally my whole .git/objects/* folder recursively.
So I lost some important scripts that I need to generate the homepage documentation. I plan to brute force the missing bits (space and tab values preceding newline, ie. trailing whitespace) to make the object files match their sha again. Wish me luck.