CLI Revamp.

[BrianPugh]

The old CLI had some quirks that made it a bit cumbersome/odd to use when compared to standard CLI tools. This PR aims to make it more idiomatic to use.

Migration Guide/Changelog

• Required keyword --convert with options {"c2e", e2c", "e2p"} is now positional and can be thought of as subcommands under the same names.

c2e

• --i input path is now positional input. convert360 c2e INPUT OUTPUT
• --o output path is now positional output. convert360 c2e INPUT OUTPUT
• --h is now --height or -h and is (still) required.
• --w is now --width or -w and is (still) required.
• --format or -f now allows you to set whether the input cubemap is dice or horizon.
• --mode now also has short option -m for setting interpolation type.

e2c

• --i input path is now positional input. convert360 e2c INPUT OUTPUT
• --o output path is now positional output. convert360 e2c INPUT OUTPUT
• --h is now --height or -h and is (still) required.
• --w is now --width or -w and is (still) required.
• Alternative to supplying --height and --width, there is now --size -s. This is the side-length of each resulting cube face in pixels.
• --format or -f now allows you to set whether the output cubemap should be dice or horizon.
• --mode now also has short option -m for setting interpolation type.

e2p

• --i input path is now positional input. convert360 e2p INPUT OUTPUT
• --o output path is now positional output. convert360 e2p INPUT OUTPUT
• --h_fov is now --h-fov.
• --v_fov is now --v-fov.
• --u_deg is now --yaw
• --v_deg is now --pitch
• --in_rot_deg is now --roll
• --mode now also has short option -m for setting interpolation type.