add default macro file (forgotten earlier)

PyTeX/format/default_macros.py

@@ -0,0 +1,18 @@
+from .macros import *
+
+
+def make_simple_macro(name: str, arg):
+    return SimpleMacro(
+        name,
+        MacroReplacement(
+            '%s',
+            arg
+        )
+    )
+
+
+def get_default_macros():
+    return [
+        make_simple_macro('!', FormatterProperty.file_prefix),
+        make_simple_macro('name', FormatterProperty.name)
+    ]