mccode-r: possibly enable to perform parameter scans from the simulation itself

[farhi]

This is to use directly simulations to scan parameters and output scan data set, instead of using mcrun and artificially re-generate a valid McStas format scan file. Also generate a proper mcstas.dat which gathers all integrated counts, even for single simulations.

[farhi]

Suggestion: Scan intervals will be specified with ':' separator for range and ',' for explicitly specified values, e.g.:

par1=1:10 -N 11 scan pars1 from 1 to 10 in 11 steps pars=1,2,3,6,7,8 scans par1 with 6 steps, using specified values

Basic mechanism is already in mccode-r.c (Feb 17th 2010) with the 'content' file (functions: mcdetector_register, mcdetector_write_content). Remaining: store steps to simulate, assemble all simulation steps into an upper level content.sim file. The mcrun/mxrun perl script currently generates non conform data file formats. Suggestion is to adapt mcplot to handle the new 'content' file, which is a detector-like file.