Handle datetime aware objects in DateTimeLine

Currently, "aware" datetime objects are not handled properly in DateTimeLine graphs. They are converted to "naive" objects, so timezones can not be set correctly.
The only way is to previously convert datetime objects to naive type, avoiding UTC conversion of them when drawing DateTime related graphs.
I'll try to find some time to take a look at the code for a patch
Regards

Start by locating the DateTimeLine implementation and tracing how aware datetime objects are converted before graphs are drawn. Reproduce the issue with timezone-aware datetimes and verify that timezone information is preserved without requiring callers to convert them to naive objects.

Written by the indexing model from the issue text.