Bolero 0.15 released

Update to Elmish 3.0, improvements to element binders and various fixes.

We are happy to announce the release of Bolero version 0.15. Bolero is a library that enables writing full-stack applications in F#, whose client side runs in WebAssembly using Blazor.

This release requires the .NET Core SDK version 3.1.402, which you can download here for Windows, OSX or Linux.

Install the latest project template with:

dotnet new -i Bolero.Templates::0.15.4

Features

#56: Update to Elmish 3.0. Also update the Cmd module to match Elmish 3's API, adding submodules Cmd.OfAuthorized and Cmd.OfJS.
#163 Rework the HTML element reference API and add Blazor component reference:
- ElementRefBinder renamed to HtmlRef (old name still available but obsolete)
- attr.bindRef renamed to attr.ref (old name still available but obsolete)
- attr.ref taking a function removed
- ref.Ref renamed to ref.Value
```
let theDiv = HtmlRef()    // Used to be: let theDiv = ElementRefBinder()

div [
    attr.ref theDiv    // Used to be: attr.bindRef theDiv
    on.click (fun _ -> doSomethingWith theDiv.Value)    // Used to be: doSomethingWith theDiv.Ref
] []
```
- Added Ref<'Component> which provides the same capability for Blazor components, using the same attr.ref:
```
let theComp = Ref<MyComponent>()

comp<MyComponent> [
    attr.ref theComp
    on.click (fun _ -> doSomethingWith theComp.Value)
] []
```
#168: Move the module Bolero.Html to a separate assembly and make all of its functions inline, in order to reduce the downloaded binary size.

Fixes

#144: When a router is enabled and the user clicks a link that points to a URI not handled by the router, do navigate to this URI.
#166: Ensure that Elmish subscriptions and init commands are not run during server-side prerender.
#174: Change ShouldRender to invoke override instead of base implementation (thanks @dougquidd!)
#175: Do not render Ref until after Child Content (thanks @dougquidd!)

Happy coding!