add class formatter. fix typo in error message

class_formatter.py

@@ -0,0 +1,11 @@
+from formatter import Formatter
+from config import DEFAULT_AUTHOR
+from replacements import make_default_commands
+
+
+class ClassFormatter(Formatter):
+    def __init__(self, class_name: str, author: str = DEFAULT_AUTHOR, extra_header: str = ''):
+        Formatter.__init__(self, class_name, author, extra_header, '.cls')
+
+    def make_default_macros(self):
+        make_default_commands(self, 'class')

replacements.py

@@ -52,7 +52,7 @@ def make_default_commands(formatter: Formatter, latex_file_type: str):
                                   info=Args.one, Type=latex_file_type.capitalize())
     formatter.add_arg_replacement(1, 'warning', r'\{Type}Warning{{{name}}}{{{warning}}}',
                                   name=Attributes.name_lowercase, warning=Args.one, Type=latex_file_type.capitalize())
-    formatter.add_arg_replacement(1, 'error', r'\{Type}Error{{{name}}}{{{error}}}}',
+    formatter.add_arg_replacement(1, 'error', r'\{Type}Error{{{name}}}{{{error}}}',
                                   name=Attributes.name_lowercase, error=Args.one, Type=latex_file_type.capitalize())
     formatter.add_replacement('end options x',
                                       r"\DeclareOptionX*{{\{Type}Warning{{{name_lowercase}}}"