parse_datetime and format_datetime

[Matt Sisk]

Just out of curiousity...why the '_datetime' suffix on these methods? 
Isn't that redundant? Or was it assuming that these methods might be 
showing up in classes outside of the DateTime namespace?

And speaking of brevity...the 0.18 docs for DateTime say that 
'time_zone_long_name' is short for $dt->tz->name. I see no evidence of a 
'tz' method, though it'd be nice to have around, along with 'tz_name', etc.

Thanks,
Matt