Add support for docopt's [options] shortcut (closes issue docopt#22)

When the [options] shortcut is detected on the usage section, we use the
contents of the options section to get the full list of options, rather
than
just getting those options that are explicitly mentioned on the usage
section.

docopt_c.py

@@ -99,25 +99,32 @@ def c_if_option(o):
                 c_name(o.long or o.short))
 
 
-def parse_leafs(pattern):
+def parse_leafs(pattern, all_options):
+    options_shortcut = False
     leafs = []
     queue = [(0, pattern)]
     while queue:
         level, node = queue.pop(-1)  # depth-first search
-        if hasattr(node, 'children'):
+        if not options_shortcut and type(node) == docopt.OptionsShortcut:
+            options_shortcut = True
+        elif hasattr(node, 'children'):
             children = [((level + 1), child) for child in node.children]
             children.reverse()
             queue.extend(children)
         else:
             if node not in leafs:
                 leafs.append(node)
-    leafs.sort(key=lambda e: e.name)
+    sort_by_name = lambda e: e.name
+    leafs.sort(key=sort_by_name)
     commands = [leaf for leaf in leafs if type(leaf) == docopt.Command]
     arguments = [leaf for leaf in leafs if type(leaf) == docopt.Argument]
-    flags = [leaf for leaf in leafs
-                  if type(leaf) == docopt.Option and leaf.argcount == 0]
-    options = [leaf for leaf in leafs
-                    if type(leaf) == docopt.Option and leaf.argcount > 0]
+    if options_shortcut:
+        option_leafs = all_options
+        option_leafs.sort(key=sort_by_name)
+    else:
+        option_leafs = [leaf for leaf in leafs if type(leaf) == docopt.Option]
+    flags = [leaf for leaf in option_leafs if leaf.argcount == 0]
+    options = [leaf for leaf in option_leafs if  leaf.argcount > 0]
     leafs = [i for sl in [commands, arguments, flags, options] for i in sl]
     return leafs, commands, arguments, flags, options
 
@@ -149,9 +156,9 @@ def parse_leafs(pattern):
     if isinstance(usage, list):
         raise docopt.DocoptLanguageError(''.join(usage))
 
-    options = docopt.parse_defaults(doc)
-    pattern = docopt.parse_pattern(docopt.formal_usage(usage), options)
-    leafs, commands, arguments, flags, options = parse_leafs(pattern)
+    all_options = docopt.parse_defaults(doc)
+    pattern = docopt.parse_pattern(docopt.formal_usage(usage), all_options)
+    leafs, commands, arguments, flags, options = parse_leafs(pattern, all_options)
 
     t_commands = ';\n    '.join('int %s' % c_name(cmd.name)
                                 for cmd in commands)