add ColorPicker button with a default xwt based backend
[GTK] add color picker backend
#327 - fix save dialog window on mac
Merge remote-tracking branch 'mono/master' into add-color-picker

Conflicts:
	Xwt.Gtk/Xwt.Gtk.csproj
	Xwt/Xwt.csproj
[Mac] add cursor support
[Mac] add CursorType.Move

swap hand cursors:
* CursorType.Help -> NSCursor.OpenHandCursor
* CursorType.Move -> NSCursor.ClosedHandCursor
fix window size for windows without content

(fixes #336)
[WPF] Fix high-DPI image scaling

This should fix issue #401.
Fix build
Merge branch 'add-mac-cursor-support' of https://github.com/sevoku/xwt into sevoku-add-mac-cursor-support

Conflicts:
	Xwt.Mac/Xwt.Mac/ViewBackend.cs
Merge branch 'sevoku-add-mac-cursor-support'
Merge pull request #366 from Strnadj/macsavedialog

[MAC] Fix SaveDialog view not works on cocoa - #327
Merge branch 'add-color-picker' of https://github.com/sevoku/xwt into sevoku-add-color-picker

Conflicts:
	TestApps/Samples/Samples/ColorSelectorSample.cs
	Xwt.Gtk/Xwt.Gtk.csproj
	Xwt.Gtk/Xwt.Gtk3.csproj
	Xwt.Gtk/Xwt.GtkBackend/GtkEngine.cs
Merge branch 'sevoku-add-color-picker'
take decoration size into account for initial size
[Mac] Add native implementation of ColorPicker
Add missing event mapping in ColorPicker
[Mac] Fix crash when checking if a widget has a native parent
Throw exception if event mapping is invalid
Merge pull request #393 from sevoku/fix-336

fix window size for windows without content