Modified the check for the spectrum_id being a string, a list is now accepted as well.
This is needed to implement the list of spectrum_id as in 'test_suite/system_tests/peak_lists.py' (test_read_peak_list_generic2() function).
Should the RelaxStrError be changed to something like a RelaxStrListError ?
Authored by: semor 2008-12-04
Parent: [r8136]
Child: [r8138]
