Remove totally useless introduction paragraph in building documentation.
We don't need Graphviz for Doxygen docs anymore.

The diagrams were useless anyway.
Mention that both target and native Corrade is needed for crosscompiling.
Improve sectioning in building documentation even more.
Fixed segfault in AbstractTexture::bind().

Caused in 6ee2745503bf056185f111d6faeb1f2491210af6, I accidentaly
removed code that initialized the array to proper length. Again I
experienced how useful unit tests for GL functionality would be.
Fix installation dir for DLLs on Windows.

Similar change to mosra/corrade@8fbedb0df2557e8b18acbb358b83bd93d7da7e20.
SceneGraph: hide internal transformation implementation from public API.

Previously it was possible to access internal transformation
implementation from Transformation and thus also from Object, e.g.:

    typedef SceneGraph::Object<SceneGraph::MatrixTransformation2D> Object2D;

    Object2D o;
    o.fromMatrix(...); // What does this here and why it returns matrix?!

Now everything is hidden in Implementation namespace and all
traces of previous code are removed from documentation. It might now be
slightly harder for users to implement their own transformation
implementations, but it wasn't easy before either. The widely used ones
are already implemented, so it shouldn't be too much of a problem.
Similarly for potential backward compatibility issues, I assume nobody
needed to implement their own transformation yet.
Make Doxygen spit less warnings.

Oh where are the times when Doxygen didn't spit ANY warning.
SceneGraph: fire assertions only where it really matters.

Should speed things up a bit in debug builds, as the asserts are now not
fired in functions which would not trigger them anyway, such as
normalizeRotation(), resetTransformation() etc.
SceneGraph: doc++
SceneGraph: clean up the code a bit.

No need to copy `return static_cast<...>;` all over the place.
SceneGraph: clean up includes.

Why did we need to include <vector> for scene graph transformations?!
SceneGraph: test assert in DualQuaternionTransformation::fromMatrix().
SceneGraph: new AbstractTranslation transformation interface.

Supports also integer coordinates.
SceneGraph: new TranslationTransformation class.

Translation-only transformation, supports also integer coordinates.
FindMagnum.cmake: minor typographic fixes.
Platform: don't use absolute include path.
Removed forward declaration of std::hash.

Aside from the fact that we shouldn't have done it at all, it caused at
least two roblems:

 1. std::hash is by standard defined as struct, but GCC's libstdc++
    defined it as class, causing Clang warning (probably harmless, but
    annoying).
 2. Clang's libcxx implements STL in inline namespace std::__1, which
    causes the forward declaration to define a completely new struct,
    different to std::__1::hash. The actual template specialization
    std::hash<ResourceKey> would then be totally unrelated to
    std::__1::hash, causing compiler error. Removing the forward
    declaration solves this, as it's possible to do the specialization
    without knowing about the inline namespace.
Platform: markup improvements for web applications.

Indented and cleaned up cruft from HTML template, renamed
NaClApplication.css to WebApplication.css, as it is universal and not
tied only to NaCl.
Move toolchains updating to crosscompiling documentation, clean up.