Redid dict() keys for unit test of find_intensity_keys(), to pass on Python 3.2 and 3.3.
Work in progress for Bug #21344, (https://gna.org/bugs/?21344) - Handling of in sparse acquired R1rho dataset with missing combinations of time and spin-lock field strengths.
This is a response to message: http://thread.gmane.org/gmane.science.nmr.relax.devel/5132 .
