Expanded the functionality of the lib.spectrum.sparky.read_list() function.

Now the dimensionality of the peak list is automatically determined, and all peak lists from 1D to
4D are supported.  The chemical shifts are also automatically detected and extracted from the list
and placed into the peak list object.  The peak intensity data is also automatically detected,
therefore the int_col argument is no longer used.
The lib.spectrum.sparky.read_list() function can now auto-detect the peak volume column and use it for intensities.