added DS_store to ignore and test edit

.gitignore

@@ -90,5 +90,7 @@ ENV/
 
 # pycharm
 .idea/
+# Mac
+.DS_Store
 # Rever
 rever/

diffpy/pdfmorph/pdfmorphapp.py

@@ -58,7 +58,8 @@ def createOptionParser():
     group = optparse.OptionGroup(parser, "Manipulations",
             """These options select the manipulations that are to be applied to
 the PDF from FILE1. The passed values will be refined unless specifically
-excluded with the -a or -x options.""")
+excluded with the -a or -x options. If no option is specified, the PDFs from FILE1 and FILE2 will
+be plotted without any manipulations.""")
     parser.add_option_group(group)
     group.add_option('-a', '--apply', action="store_false", dest="refine",
             help="Apply manipulations but do not refine.")

doc/source/index.rst

@@ -20,7 +20,7 @@ scale due to differences in incident flux, for example. ``PDFmorph`` will
 do its best to correct for these benign effects before computing and 
 plotting the difference curve. One measured PDF (typically that 
 collected under higher temperature) is identified as the target PDF and 
-the second PDF is then morphed by "stretching" (chaning the r-axis to 
+the second PDF is then morphed by "stretching" (changing the r-axis to
 simulate a uniform lattice expansion), "smearing" (broadening peaks 
 through a uniform convolution to simulate increased thermal motion), and 
 "scaling" (self-explanatory). PDFmorph will vary the amplitude of the 
@@ -29,6 +29,8 @@ the target PDFs, then plot them on top of each other with the difference
 plotted below.
 
 There are also a few other morphing transformations in the program.
+If no morphing transformation is specified, ``PDFmorph`` will return just
+the plotted PDFs.
 
 Finally, we note that though ``PDFmorph`` should work on other spectra 
 that are not PDFs, it has not been extensively tested beyond the PDF.