Data trigger expressions / Inline converters

It was always very annoying to create `IValueConverter` for everything. My proposal is to create a new type of trigger or extend DataTrigger so it could support expressions.

There's already a project for that but seems dead: https://github.com/JohannesMoersch/QuickConverter

It compiles expressions at runtime while built-in feature could do it at compile time. Having intellisense for that would be sweet but not necessary.

Every major JS framework support that, see how easy it is in Vue.js for example: https://vuejs.org/v2/guide/conditional.html

That would be a breath of fresh air.

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There are still many other things that I hate about XAML/WPF like each XAML file is bloated with long namespaces like `xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"`. It would be great if it was implicit and not needed at all. Also, 2006 in the path makes you feel like you're using some outdated technology from 2006. IMHO XAML files should be as clean as possible.