relax SVN archive

Comment fix for the target_functions/relax_fit.c file.

Removed the comment and docstring saying that the exponential curve-fitting gradient is unimplemented.

Shifted all of the parameter Python lists to C arrays into the new param_to_c() function.

This is for the target_functions.relax_fit C module to avoid much duplicated code.

Changed the array declarations in the target_functions/c_chi2 C file and header.

Instead of using the pointer format of *xyz, the array format of xyz[] is now being used. These are
equivalent and the later is more obvious that this is an array.

Changed the array declarations in the target_functions/exponential C file and header.

Instead of using the pointer format of *xyz, the array format of xyz[] is now being used. These are
equivalent and the later is more obvious that this is an array.

More removal of code.

task #7822(https://gna.org/task/index.php?7822): Implement user function to estimate R2eff and associated errors for exponential curve fitting.

Removed all unnessary code from estimate R2eff module.

task #7822(https://gna.org/task/index.php?7822): Implement user function to estimate R2eff and associated errors for exponential curve fitting.

Modified verify error script, to use new estimate R2eff module.

task #7822(https://gna.org/task/index.php?7822): Implement user function to estimate R2eff and associated errors for exponential curve fitting.

Modified profiling script to use the new estimate R2eff module.

task #7822(https://gna.org/task/index.php?7822): Implement user function to estimate R2eff and associated errors for exponential curve fitting.

Added initial documentation for multifit_covar.

task #7822(https://gna.org/task/index.php?7822): Implement user function to estimate R2eff and associated errors for exponential curve fitting.