Player Calibrator Flip Option

[P-Star7]

Is your feature request related to a problem? Please describe.
I dislike having to manually flip and paste sprites on the other side of the sheet. It's especially confusing because it is not a simple horizontal flip of the left or right half of the sprite sheet, and needs either manual work from the artist or a program that knows where to mirror and paste the sprites, which is where this feature comes into play.

Describe the solution you'd like
The player calibrator to have options to flip the left or right halves of it to automatically complete the sheet, as well as to consider hitboxes. There are seven main character sheet formats that SMBX uses to animate its players, detailed below. The user would select a format that they want to auto-flip, specify whether the left or right side is the side that needs automatically completed (for example, if "left" is selected, the sprites from the right side of the sheet are mirrored to the left side), and press the button to do it.

Additional context
I require this for work on TheXTech "two players playing as the same character" costumes.

List of player formats:

• mario-1/luigi-1
• mario-2,3,6,7/luigi-2,3,6,7
• mario-4,5/luigi-4,5
• peach-1/toad-1
• peach-2,3,6,7/toad-2,3,6,7
• peach-4,5/toad-4,5
• link-1,2,3,4,5,6,7

Some character formats have redundancies such as mario-2 not having the shooting frames of mario-3, or peach-4 not having the running and flying frames of toad-4. However, if the artist keeps these areas invisible in the mario-2 or peach-4 sheets, then they will just be "reflected" as invisible areas and it won't matter.

[P-Star7]

Actually, I am unsure if all the 2-7 Marios and Luigis and 2-7 Peaches and Toads use the same format. That might vastly simplify the setup. See:
TheXTech/TheXTech#297