Let argparse print default values
Let argparse print default values

Use a formatter for argparse to print default values instead of doing
this manually.

eric-seekas/pannellum,riuson/pannellum,Benvii/pannellum,Benvii/pannellum,riuson/pannellum,quentinyang/pannellum,eric-seekas/pannellum,mpetroff/pannellum,psteph801/psteph801.github.io,Benvii/pannellum,riuson/pannellum,riuson/pannellum,quentinyang/pannellum,quentinyang/pannellum,psteph801/psteph801.github.io,ywjrg/pannellum,psteph801/psteph801.github.io,eric-seekas/pannellum,Benvii/pannellum,ywjrg/pannellum,ywjrg/pannellum,mpetroff/pannellum,ywjrg/pannellum,mpetroff/pannellum,psteph801/psteph801.github.io,mpetroff/pannellum,quentinyang/pannellum,eric-seekas/pannellum