Improve user experience

[GuiMacielPereira]

Upon discussing the usability of the current package with the scientists, we agreed on several improvements that should be made:

• Re-running y-space fit should not override the results of previous y-space fits
• Fitting results should be easily exportable (ASCII) to other software
• Workspace names should be *shortened where possible
• Add residuals curve to figures
• Workspaces containing Minuit fit results should be consistent with workspaces from Mantid Fit (e.g. naming of rows)
• Global fit plots with option 'ALL' should show sum of plots and sum of fits
• Log output should be saved as a text file, as well as an additional log file that includes only the important information (e.g. fitting results)