Physics shape rework #6: removed unneded overload, fixed the original.
Physics: complete the definition for ShapeGroup.
SceneGraph: added Object::setParentKeepTransformation().
Physics shape rework #7: renamed Physics namespace to Shapes.
Shape rework #8: updated documentation.
Math: fixed matrix tests (spotted by Clang).

Either GCC 4.8 poorly implements C++11 or it already has support for
some proposed C++14 feature, which allows to elide successive
initializer braces.
Math::Geometry: cleaned up Distance test.

Everything is working as expected, which is ahem... unexpected.
Math::Geometry: cleaned up Distance, removed use of Matrix.

The same functionality is now provided in Vector2::cross() which is
also more meaningful.
Use `\bot` instead of `\perp` in math formulas.

`\perp` is for relations, `\bot` is usable as "name". Thanks @JanDupal
for hints :-)
Make Shader::addSource() no-op for empty string.
Make Shader::addSource() move-aware.

Also update addFile() to prevent unnecessary copying.
Shaders: added first version of MeshVisualizer shader.

Rudely written to work only with fairly recent extensions and nothing
less than GLSL 3.30. It requires geometry shaders for wireframe
rendering, without it it behaves the same as Shaders::Flat.
First C++14 TODO :-)
Math: added convenience function Vector::resized().
Math: don't include <algorithm> in header file.

31ce072f39513277a70d1d3611814cdc0a261635 was wrong, this header is
harmful. This beast includes ~46k LOC, much more than <*stream> class of
headers. Rewritten min() and max() manually, which surprisingly leads to
shorter implementation than previously. Compilation time on my machine
reduced from ~4:30 to ~4:21, not bad.
SceneGraph: FeatureGroup compilation optimization.

Created less-templated base for FeatureGroup and moved its
implementation into *.hpp file, allowing to remove <algorithm> header
from FeatureGroup.h (and meanwhile removing forgotten one also from
AbstractGroupedFeature.h). Saved another ~10 seconds of compilation time
(previously ~4:21, now ~4:11).
SceneGraph: AbstractFeature compilation optimization.

Constructor, destructor and all virtual functions are moved into
implementation file, so they don't need to be recreated and add into
binary on every usage. Should save a bit on resulting file size.
SceneGraph: removed superfluous instantiation sources.

Moved almost everything into one file, instead of compiling ~50k LOC
seven times it is now compiling 56k LOC only once. This saves another ~5
seconds of compilation time (before ~4:11, now ~4:06).

Also explicitly saying that we are instantiating Float version of all
classes. In the future we might have compile switch for building also
Double one, this helps with consistency.
Doc++
Doxygen workarounds.