[All?] Fix exploit allowing color control characters to be used in chat under certain circumstances

[AndrewBetson]

Description

This PR fixes an oversight that causes the ReadChatTextString function to skip over color control characters if they are preceded by either of the hex color control codes.

This happens because the inner for-loop increments test one too many times, causing any following color control characters to be skipped over when the outer for-loop increments test, itself.

As far as I can tell, this effects all SDK2013 games.

The following screenshots use the example string �color!��FFD700test (0x07636F6C6F7221070546464437303074657374), generated with https://sourcecolors.neocities.org/

Before	After

[AzureWoof]

This doesn't seem all too harmful. Would much rather this be a feature, with some restrictions of course.

[origintopleft]

So far this has exactly one "malicious" use: Faking item drops. I learned about this when someone faked getting a Valve Rocket Launcher. (I chose something that doesn't actually exist in the game as proof of concept)

I don't know how much this is considered a critical thing to fix, but if we can accept this as a thing people do, I'd vote in favor of people having colored text chat (if changed to something like Quake's system, with ^ suffixed by a value)