Fix incorrect merging of in-field and out-of-field loop coefficients

Fixed bug from changes to plot_map.

Updated the SVD call to use the new process.

Allow fitting against arbitrary dimension name.

Fixed the _maxDataChunk and _max_pos_per_read attributes being set to 1

Moved the code to convert the slice dictionary to lists of indices to it's own method, get_pos_spec_slices

Don't add colorbars to plots from within the plot_map function.  It is handled in plot_map_stack itself.