* use opengl 3.2/4.1 core on os x
 * updated xcode project
 * fixed permissions ...
 * added (wip) double/triple/*-buffering support (the default "framebuffer" is now a vector containing one or more framebuffer objects that will be used in a "ping-pong"/modulo way); in the future, there will be a separate thread/process/opengl-context that will handle the framebuffer swap (read data from the opencl buffer, write it to an opengl texture and finally display it), which should give a good performance improvement
 * note: on certain implementations and hardware setups this might already give a 2x performance improvement when using double buffering