First tries using McStas

[Kristian Nielsen]

Hi Georg,

I finished the modified Source component and put it on the following
URL:

http://elu-alf-2.risoe.dk/~elu-krni/mcstas/support/misc/Source_flux.comp

It is similar to the Source_flat component, but takes an extra
parameter 'flux': the absolute flux of the source in neutrons per cm^2 per AA
per steradian. It sets the initial weight of neutrons so that the
intensities in detectors computed by McStas model absolute intensities.

 - Kristian.