Initial work for GCC 4.5 compatibility.

GCC 4.5 doesn't know constexpr keyword and nullptr. As all constexpr
functions are here inline, it can be done with a simple macro.
GCC 4.5 compatibility: missing headers.
GCC 4.5 compatibility: GCC badly optimizes Matrix4::rotation*().

Redone in a way that the unit test passes.
GCC 4.5 compatibility: removed range-based for cycles.
GCC 4.5 compatibility: worked around "Sorry, not implemented" error.

SizeBasedCall is internally used only in MeshTools::compressIndices(),
modified the function to not use variadic templates, only the one
parameter used in compressIndices().
GCC 4.5 compatibility: Probably can't use initializer list here.
Initial work for GCC 4.4 compatibility.

GCC 4.4 compatibility also enables GCC 4.5 compatibility.
GCC 4.4 compatibility: missing headers.
GCC 4.4 compatibility: worked around "Sorry, not implemented" error.

New function declaration syntax for deduced return types doesn't work
here fully yet.
GCC 4.4 compatibility: std::unordered_map::reserve() doesn't exist yet.
GCC 4.4 compatibility: lambda functions aren't supported yet.
GCC 4.4 compatibility: workaround for initializer list.
CMake < 2.8.8 compatibility.

 * No OBJECT library targets - compilation with unit tests will take a
   lot more time.
 * No HANDLE_COMPONENTS in FindPackageHandleStandardArgs - added copy of
   the file (and its dependencies) from CMake 2.8.8.
Merge branch 'master' into compatibility

Conflicts:
	src/CMakeLists.txt
	src/MeshTools/CMakeLists.txt
Forgot to install also magnumCompatibility.h header.
Merge branch 'master' into compatibility
Re-enabled RTTI from eb82cb462a2d853df142cccfa09a0f402efd8f82.

It causes too many linking problems in depending projects and IMHO it's
not good to force disabling RTTI in everything depending on Magnum.
Merge branch 'master' into compatibility
Merge branch 'master' into compatibility

Conflicts:
	src/CMakeLists.txt
	src/Math/Test/CMakeLists.txt
	src/Math/Test/MathTypeTraitsTest.cpp
	src/MeshTools/Test/TipsifyTest.h
	src/Physics/Test/ShapeGroupTest.cpp
Disable -Wdouble-promotion for GCC 4.5.