relax SVN archive

Shifted the tag name prefix creation code into bmrblib.tag_category.TagCategory.

Created the heteronucl_NOEs and heteronucl_T2_relaxation saveframes.

Created the T1 tag category.

Further object simplifications.

The __init__() methods have been shifted into the TagCategory base class in bmrblib.tag_category.

Code simplification by placement of many objects into the saveframe namespace.

Created the unused HeteronuclT1Software tag category class.

Created the HeteronuclT1Experiment tag category object.

Split up the T1 saveframe object.

The main object is now called HeteronuclT1Saveframe. The HeteronuclT1List tag category has been
shifted into its own object, and the other tag categories will be created next.

Shifted the code for the relaxation data into bmrblib.kinetics.heteronucl_T1_relaxation.

Created a package for the support of the supergroup 6 collection of saveframes (kinetic data).