[FormatConverter] Fix improper init order

Author: mpsonntag

odml/tools/converters/__init__.py

@@ -1,2 +1,3 @@
-from .format_converter import FormatConverter
 from .version_converter import VersionConverter
+# FormatConverter depends on VersionConverter
+from .format_converter import FormatConverter

odml/tools/converters/format_converter.py

@@ -4,8 +4,9 @@
 import sys
 
 import odml
-from ..rdf_converter import RDFWriter
-from .version_converter import VersionConverter
+
+from .. import RDFWriter
+from . import VersionConverter
 from ..utils import ConversionFormats
 
 try: