Fix parser a bit

py/hexagram/path.py

@@ -27,12 +27,10 @@ class PathCommand():
         self.arg += ch
 
     def arg_next(self, ch: str):
-        if len(self.arg) == 0:
-            return
-
-        self.arg += ch
+        if len(self.arg) > 0:
             self.args.append(self.arg)
-        self.arg = ''
+
+        self.arg = ch
 
     def arg_finish(self):
         if len(self.arg) > 0:
@@ -115,6 +113,8 @@ class Path():
                     command.set_command(ch)
                 elif Path.is_number(c):
                     command.arg_addch(ch)
+                elif ch == '-':
+                    command.arg_next(ch)
                 elif ch == ' ' or ch == ',':
                     state = State.INT
                     command.arg_finish()