Improve blender exporter UI

[cg-cnu]

Hey,
blender exporter users out there…
I am working on cleaning up the ui. github issue

Any feedback is welcome

[FrankSilvaHM]

YES!!! Huge improvement! Thank you thank you thank you!!

[AlexandreRangel]

Thank you!

[cg-cnu]

Thanks for the guys! Pushed the changes, hope will land up in blender soon