hawkmoth: add option to dump cursor cache info

This may be helpful in tuning the cache size.

src/hawkmoth/__main__.py

@@ -15,6 +15,7 @@
 from hawkmoth.ext import napoleon
 from hawkmoth.parser import parse
 from hawkmoth.util import doccompat
+from hawkmoth.doccursor import DocCursor
 
 def filename(file):
     if os.path.isfile(file):
@@ -76,6 +77,9 @@ def main():
                         help='Argument to pass to Clang. May be specified multiple times. See cautodoc_clang.')  # noqa: E501
     parser.add_argument('--verbose', dest='verbose', action='store_true',
                         help='Verbose output.')
+    parser.add_argument('--cursor-cache-info', dest='cursor_cache_info',
+                        action='store_true',
+                        help='Print cursor cache information.')
     parser.add_argument('--version', action='version',
                         version=f'%(prog)s {_read_version()}',
                         help='Show version and exit')
@@ -97,5 +101,9 @@ def main():
     for error in errors:
         print(f'{error.level.name}: {error.get_message()}', file=sys.stderr)
 
+    if args.cursor_cache_info:
+        print('>>> Cursor cache info:')
+        print(DocCursor.cache_info())
+
 if __name__ == '__main__':
     main()