relax SVN archive

Implemented the lib.periodic_table.periodic_table.atomic_weight() method.

This returns the standard atomic weight of the atom as a float.

Created the unit test infrastructure for the lib.periodic_table module.

This includes one unit test of the lib.periodic_table.periodic_table.atomic_weight() function which
has not been implemented yet.

Fix for an accidental mistake in the lib.periodic_table module.

The lib.periodic_table method for adding elements is now private.

Added all of the IUPAC 2011 atomic weights to the lib.periodic_table module.

These will be useful for correctly calculating the centre of mass of a molecule.

Tried to improve docstring for API documentation.

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

Fix for warning message in the auto analyses in the GUI.

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

Modified test_estimate_r2eff_err_auto, to set r1_fit to False.

This still make the systemtest pass, and fit R1.

So this means R1 fit button is not functioning properly.

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

Modified systemtest 'test_estimate_r2eff_err_auto', to use the GUI script.

It seems to work Ãperfect.

This is to test against GUI script:
test_r2eff_err_estimate

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

Formatting changes for the lib.periodic_table module.

This is in preparation for extending the information content of this module.