added #error directive

Author: Laurent Pinson

pypreprocessor/__init__.py

@@ -317,6 +317,11 @@ def lexer(self, line):
                     print('Warning trying to remove more blocks than present', 
                           self.input, self.__linenum)
 
+        elif self.__is_directive(line, 'error'):
+            print('File: "' + self.input + '", line ' + str(self.__linenum + 1))
+            print('Error directive reached')
+            sys.exit(1)
+
         else: 
             # escapechar + space ==> comment
             # starts with #!/ ==> shebang