related to #152
factoryze all the OpenCL allocation and release

I created two dunctions in the opencl module which are used in
the ocl_xxx modules to allocate and release the pyopencl.Buffer
memory.

please check that all unit test are working.
This should fix issue #133
If platforms are available but no devices: deactivate OpenCL
Correct typo in Fred's patch
Related to #133
new todo
Merge branch 'devel'
make-up of todo-list
Update documentation regarding MacOSX
add unit test for all calibrants fake images

a fake image is generated for all detectors.
a with_plot parameter can be set to True to generate a fake.pdf
file with all the images.
Small modifications ...
* Register "Detector" (needed for GUI)
* limit tests to <5s
Put letters in bold/large font & black for peak-picking