Animation: added a collection of easing functions.

This was tremendous fun to make.

doc/changelog.dox

@@ -40,6 +40,15 @@ See also:
 
 @subsection changelog-latest-new New features
 
+@subsubsection changelog-latest-new-animation Animation library
+
+-   New @ref Animation::Easing namespace with a collection of well-documented
+    easing functions
+-   New @ref Animation::ease(), @ref Animation::easeClamped(),
+    @ref Animation::unpack(), @ref Animation::unpackEase() and
+    @ref Animation::unpackEaseClamped() utilities for combining interpolators
+    with easing functions and/or unpackers
+
 @subsubsection changelog-latest-new-math Math library
 
 -   Support for using the @ref Math::Deg, @ref Math::Rad, @ref Math::Half,

doc/generated/CMakeLists.txt

@@ -46,6 +46,10 @@ else()
     message(FATAL_ERROR "No windowless application available on this platform")
 endif()
 
+add_executable(easings easings.cpp)
+target_link_libraries(easings
+    Magnum::Magnum)
+
 add_executable(shaders shaders.cpp)
 target_link_libraries(shaders
     Magnum::Magnum