Set mono as default for pymol. Pymol stereo can still be run with `pymol -S`

pymol_disable_stereo.diff

diff --git a/modules/pymol/__init__.py b/modules/pymol/__init__.py
index 3b95856..a28970a 100644
--- a/modules/pymol/__init__.py
+++ b/modules/pymol/__init__.py
@@ -163,6 +163,12 @@ if pymol_launch != 3: # if this isn't a dry run
         # or via execfile(".../pymol/__init__.py",...) from main
 
         if not hasattr(__main__,"pymol_argv"):
+            try:
+                # check if explicitly stereo
+                idx_explicit_stereo = sys.argv.index("-S")
+            except ValueError:
+                # force mono
+                sys.argv += ["-M"]
             __main__.pymol_argv = sys.argv
 
         pymol_launch = -1 # non-threaded launch import flag
@@ -530,6 +536,12 @@ if pymol_launch != 3: # if this isn't a dry run
             args = pymol_argv+["-K"] # keep PyMOL thread alive
         else:
             args = list(args)
+        try:
+            # check if explicitly stereo
+            idx_explicit_stereo = args.index("-S")
+        except ValueError:
+            # force mono
+            args += ["-M"]
         if pymol_launch == 2: # spawn thread -- 'import pymol'
             global glutThreadObject
             cmd.reaper = threading.currentThread()