WebSharper.UI 4.2.1

This is the first stable release of WebSharper.UI 4.2. See the associated WebSharper release

Improvements

• #157 Add Attr.ClassPred and Attr.DynamicClassPred for adding CSS classes conditionally. ClassPred also supports the .V syntax: Attr.ClassPred "hidden" (currentPage.V = "home").
• #153 Add View.WithInit and WithInitOption.
  View.WithInit init view is equivalent to view, except that if view is in a waiting state, its initial value is init instead.
  Similarly, View.WithInitOption view is equivalent to View.Map Some view, except that if view is in a waiting state, its initial value is None instead.

Fixes

• #152 If a template only specifies one of styles and meta holes, write the content for both at that location.
• #155 Fix filling ws-on* event handlers from the server side.