FindGLUT.cmake: Add imported targets and documentation

Also let find_library really search for frameworks on OS X.
FindBoost.cmake: Add Boost::boost and Boost::<C> targets and documentation
Help: Add notes for topic 'find-module-targets'
Merge topic 'find-module-targets' into next

b5b524aa Help: Add notes for topic 'find-module-targets'
38da974d FindBoost.cmake: Add Boost::boost and Boost::<C> targets and documentation
144b255b FindGLUT.cmake: Add imported targets and documentation