relax SVN archive

Additions to the select.read() and deselect.read() docstrings.

Converted select.read() and deselect.read() to use the new relax_io.read_spin_data_file() function.

Reverted some accidental commenting out of system tests.

Removed a debugging print statement.

Fixed all the calls to sequence.read() where the default residue columns were being relied upon.

Removed the test for error values of zero, as this was killing Dasha!

Fix for the validate_sequence().

The shifted column numbers were not being taken into account.

Added the missing import of read_spin_data_file().

Yet another fix for the new read_spin_data_file() function - hopefully this will be the last!

Fix for the test_read() system test.

The residue columns must now be specified.