initial OpenCL support commit
Added find_package for opencl to cmake.
added command_dispatcher to singletons
--with-opencl now sets the CPPA_OPENCL flag
Merge branch 'unstable' of github.com:Neverlord/libcppa into topic/opencl
basic functionality added to cppa/opencl
Merge branch 'unstable' into topic/opencl

Conflicts:
	cppa.files
Added smart pointer for opencl types

Uses clRetainX and clReleaseX provided by OpenCL.
The command_dispatcher now uses event callbacks

to handle results from kernel executions.
Merge branch 'unstable' into topic/opencl

Conflicts:
	src/singleton_manager.cpp
adapt to changed actor interface
Merge branch 'unstable' into topic/opencl
bug fixes
added clFlush after enqueue

Solves a problem with amd graphic cards.
Merge branch 'unstable' into topic/opencl
Merge branch 'topic/opencl' of github.com:Neverlord/libcppa into topic/opencl
use -pthread option rather than CMake script
added get_command_dispatcher convenience function
changed calculation for size of result vector
unit test changed to different calculations

validation missing