relax SVN archive

Bug fix for the __det_pdb_element() method.

RNA PDB files with missing element information is now handled properly. The stripping of the "'"
was being ignored.

Removed a debugging print statement.

Fixes for the structure.load_spins() user function docstring for RNA/DNA work.

Modified the dna_pcs_fit.py N-state model system test script to use the truncated PDB file.

This speeds the system test up by orders of magnitude.

Created a truncated version of the LE.pdb file for the RDC and PCS system tests.

This contains just the atoms for PCS and RDCs, and will significantly speed up the tests.

Loosened a value check in the test_pcs_fit_zero_pos N-state model system test.

This was sometimes failing, but the value was correct enough.

Created the test_missing_data N-state model system test.

This should pull out a few hard to find bugs.

Wrote a script for testing the missing RDC and PCS data.

This uses the N-state model with N=1, so direct testing of the single state to 4 tensors.

Created some test RDC and PCS data to test the handling of missing data.

This includes entire data sets missing, spins missing from one type of data, and individual spins
missing.

Replace function form string module is imported.

This is used to create the dummy file entry.