Fix Portrait Dim Issue (Temporary workaround!)

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There was no conditional check before on whether the color of portraitImage is completely white or not when setting portraits to dimmedState. This fix issues which affect a lot of users on discord & forum.

Hope this can get to 3.14 release as the dim issue pretty much breaks Fungus functionality and cause problems for those making visual novel game

EDIT: After further investigating the issue, this is not a proper fix! More of a workaround and do not merge this! Perhaps, somebody with a better knowledge on how Fungus' portrait system works would pick this up.

Description

This pr partially fixes https://github.com/snozbot/fungus/issues/922

What is the current behavior?

Dim portraits would sometimes set both speaking/not-speaking characters stuck to a dimmed state

What is the new behavior?

As shown in videos below

BEFORE

https://user-images.githubusercontent.com/64100867/105013026-652a3000-5a71-11eb-884f-e7e43ebe657a.mp4

AFTER

https://user-images.githubusercontent.com/64100867/105013187-8f7bed80-5a71-11eb-92a3-c4169e354ab1.mp4

Edit: Description fix

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closing this,

[AlejandroLaraEsp]

This works great! Thank you very much!

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Yes, this fixed the Dim issue. But it's more of a temporary workaround, and it's a bit ugly tbh :/