Add helper struct which contains OpenCL event and a name

Add function which adds such struct to the profile.
Enable OSX builds.

CL headers sit under "OpenCL/*" by default, unlike all other platforms.
Merge branch 'ngaloppo-master' into devel
Update docs to reflect MacOSX support
Use of OpenMP in examples is optional
If OpenMP available, use it in examples
Closes #1 : Make examples optional