Add short options which should be treated as switches.

Previously only the long versions of options were correctly flagged
as booleans, but the -b and -B options do not have long alternatives
so they need to be supported too. And for familiarity to command line
users we should support other single-char switches too

fsl/wrappers/fast.py

@@ -35,9 +35,16 @@ def fast(imgs, out='fast', **kwargs):
 
     valmap = {
         'nobias' : wutils.SHOW_IF_TRUE,
+        'N' : wutils.SHOW_IF_TRUE,
         'verbose' : wutils.SHOW_IF_TRUE,
+        'v' : wutils.SHOW_IF_TRUE,
         'Prior' : wutils.SHOW_IF_TRUE,
+        'P' : wutils.SHOW_IF_TRUE,
         'segments' : wutils.SHOW_IF_TRUE,
+        'g' : wutils.SHOW_IF_TRUE,
+        'b' : wutils.SHOW_IF_TRUE,
+        'B' : wutils.SHOW_IF_TRUE,
+        'p' : wutils.SHOW_IF_TRUE,
     }
 
     argmap = {