Scripting: Expose Tileset.transformationFlags

[dogboydog]

Fix #3753

Examples (scripting console with a Tileset as the active asset)

>tiled.activeAsset.transformationFlags |= Tileset.AllowFlipVertically
2
> tiled.activeAsset.transformationFlags
$8 = 2
> if ((tiled.activeAsset.transformationFlags | Tileset.AllowFlipVertically) > 0) { tiled.log('vertical flip enabled'); } 
vertical flip enabled

[bjorn]

This change looks mostly fine, I only see some empty lines missing between functions and there is no @since on the new property (and needs addition to CHANGELOG.md).

Thanks for implementing this!

[dogboydog]

What should be used for @since ? I'll make the other updates too.

[bjorn]

@dogboydog Ah, for other scripting additions I've used @since 1.11.1 so I'd suggest you do the same. I may still do a 1.11.1 release after all.

[dogboydog]

Done, thanks

[dogboydog]

Sorry I forgot the changelog