Add exportZidv jython function.

[jon4than]

Hi Yuan,

I'll likely clean this up a little more, but I imagine the functionality will stay essentially the same.

Jon

Example usage:

# bring in a bundle
loadBundle('/tmp/test.xidv')

# export using DisplayAreaSubset
exportZidv('/tmp/test.zidv', 'class:ucar.unidata.idv.control.ContourPlanViewControl')

# export without using DisplayAreaSubset
exportZidv('/tmp/test.zidv', 'class:ucar.unidata.idv.control.ContourPlanViewControl', False)

[yuanho]

Jon, you probably want to let user pass null for the display control if there is no need to do the subset. Maybe create an api as exportZidv('/tmp/test.zidv') with only one input parameter.

Yuan