relax SVN archive

Added a "check" function, what will determine if R1 data is missing for a model to analyse.

Also added corresponding unit tests, to test the functionality.

Split the unit test of specific_analyses.relax_disp.checks.get_times() into its own unit test file.

Fix for correct English, replacing "where" with "whereby".

Renamed the parameter "r1_fit" to "r1".

This naming fits better to all other parameters.

Renamed R1rho off resonance models where R1 is fitted.

This removes the "underscore".
This is a better representation presented to the user, for example in the GUI model
selection list or the relax_disp.select_model user function in all UI.

Space fix in the import of variables.

Replaced remaining variable names: MODEL_PARAM_* with MODEL_LIST_*, to match all of the other MODEL_LIST_* variables.

Replaced variable name: MODEL_PARAM_INV_RELAX_TIMES with MODEL_LIST_INV_RELAX_TIMES,
to match all of the other MODEL_LIST_* variables.

Also added a newline to end of file.

Fix for comment, which mentions R2 parameter, when it relates to R1 fit.

Fix for replacing spaces " " with "_" in header files.

sr #3121(https://gna.org/support/?3121): Support request for replacing space in header files for the value.write functions.