[WPF] Error when using nested TextEntry in Notebook sample in ScrollView.
Initial suppport for multi-toolkit image support

Image objects loaded using a toolkit can now be used in
other toolkits.
Add public method for creating multi-resolution images
Improve support for cross-toolkit images

Allow specifying an image loader callback. Secondary toolkits will use it to
load images on demand.
Fix NRE
Revert "[WPF] Removed support for default text foreground, which was interfering with region foregrounds."

This introduce a regression when drawing normal text and using ctx.SetColor by forcing the color to always be black.

Although the commit did fix an issue, the only way to do it properly and take into account the current context-set color is to defer the creation of the TextFormatted instance until drawing time so that the context-bound color can be passed to TextFormatted constructor as it can't be set afterwards.

This reverts commit db439534ae067b84646b613cde20d837bfc007ea.
Add ScrollToRow method to ListView/ListBox
extend WebView functionality (incl. all backends)
* load custom html content
* go back/forward, reload, stop loading
* new properties: Title (incl. changed event), LoadProgress, CanGoBack, CanGoForward
* additional navigation and loading events
* add all new functionality to samle apps
* fix Gtk.Windows backend if inside scrolled container

Backend limitations/TODOs:
WPF: custom html doesn't work (wpf bug?)
WPF: Title needs mshtml binding
GTK: WebKit.WebView on resize: content grows but does not shrink
MAC: not tested at all
[GTK] fix RemoveSignalHandler extension method
[WPF] implement WebViewBackend.Title using script invoke
[MAC] fix url handling for OnNavigateToUrl
Merge branch 'xtookit-images'
[WPF] Track api changes

Image.ToImageDescription() now takes an ApplicationContext as argument,
so we need to pass it along everywhere that method is used.
Merge pull request #339 from sevoku/add-list-scroll-to-row

Add ScrollToRow method to ListView/ListBox
[WPF] fix TextEntry PlaceholderText initialization
PlaceholderTextAdorner should be initialized after
the backend widget has bee fully loaded.
(fixes #329)
[MAC] add missing cursor position and selection support to TextEntryBackend
Add license file
Sensitivity for WindowFrame.
Example for Window.Sensitive
Merge pull request #350 from residuum/window-sensitivity

[WPF] [GTK] Sensitivity for WindowFrame