relax SVN archive

Mass conversion to the new GLOBAL_PARAMS and SPIN_PARAMS specific API data structures.

This involves mainly the conversion of the model-free analysis to these new objects, and the
subsequent changes to how model-free parameters are handled. The parameters are now all lowercase,
for example ['S2', 'te', 'Rex'] is now ['s2', 'te', 'rex']. The follow parameters are now converted
throughout relax:
'bond_length' to 'r',
'CSA' to 'csa',
'heteronucleus' to 'heteronuc_type',
'proton' to 'proton_type'.

The regularisation of the specific analysis parameters via GLOBAL_PARAMS and SPIN_PARAMS has
significantly simplified the current code and make it much easier to introduce new analyses.

Fix for the specific API common method _return_value_general() for when spectrum IDs are not present.

Not sure why this change is necessary! This could introduce future bugs, or hide a new bug!

Updated the arg_check.is_func() function for handling class methods.

Fix for the function checking in the specific API Param_list objects.

Class methods were not being detected!

Fix for the specific API _return_conversion_factor_spin() method.

The wrong variable was being used.

Fix for the initialisation of the conversion factor storage in Param_list.

Removed spin args from return_conversion_factor() and added optimisation parameters.

The global and spin specific optimisation parameters are now set up for all specific analyses.

Created the specific function API _return_conversion_factor_spin() method.

The Param_list.get_units() method can now handle function type objects.

This is needed for the model-free Rex parameter.

Fix for the Param_list.get_conv_factor() method - the function type was not properly handled.