gif files not converted correctly

[rsedxcftvgyhbujnkiqwe]

Convert is able to target gif files, however it does not pack all of the frames in the gif into the vtf to create an animated vtf. Since '--start-frame' is a parameter I assume this is intended to be supported, however it does not work in the current state. Built the most recent version from source to confirm and it still does not work.
If this is an incorrect usage of convert, or there is some other way to put multiple frames into a vtf, I would suggest adding it into the documentation.

[JJL772]

Thanks for reporting this! I never finished the GIF implementation (or even began it, really). It's intended to be a feature eventually.

[WinterPhoenix]

I think STB's animated GIF support is shaky at best anyway... See nothings/stb#1025

That said, +1 on both fronts for proper support, please!