Simplify color scheme to use tint color

[bmnick]

Rather than having an internal color scheme which can’t be easily
inherited, move to using the tintColor of the VENTokenField to control
the color of tokens. This allows just as much customizability, while
allowing common color schemes in an application to carry over without
custom color assignments. For example, changing the global tint color
will now be inherited by the token field if changed in either the
storyboard or by setting the UIWindow’s tint color. As a side effect,
tint adjustment modes (fading colors when an alert view is displayed)
is supported.

[bmnick]

This would actually be a major point release, since it's breaking backwards compatibility. If you don't want to do that, we could keep the old selector around and label it as deprecated, keeping it down to a minor. Let me know if that's preferable.

[ayanonagon]

Deprecation would be preferable over doing another major version release, since we did one just recently, and there are some other smaller fixes we'd like to get in before then. Thanks for this! 😸

[bmnick]

I seem to be seeing an issue in my integration where the initial color (before either adding or removing a token) is incorrect. Looking into this now, I'll work on getting it fixed and push it up.

[bmnick]

It was a client-side problem - becoming first responder before the view had been laid out. Switching from viewWillAppear: to viewDidAppear: fixed it. Short of a major layout rewrite, I don't think there's much of a solution for that.