Autofloat on tiling WMs

It makes more sense to have blobdrop always floating by default.
Otherwise a tiled blobdrop window will look way too large (see demo in
#5).

Setting the window flag to dialog should usually force a floating window
on tiling WMs [0].

[0] rust-windowing/winit#862

src/qml/Main.qml

@@ -7,7 +7,7 @@ import Backend
 ApplicationWindow {
 	id: root
 	visible: Settings.needsGui
-	flags: Qt.Window | (Settings.alwaysOnTop ? Qt.WindowStaysOnTopHint : 0) | (Settings.alwaysOnBottom ? Qt.WindowStaysOnBottomHint : 0) | (Settings.frameless ? Qt.FramelessWindowHint : 0)
+	flags: Qt.Dialog | (Settings.alwaysOnTop ? Qt.WindowStaysOnTopHint : 0) | (Settings.alwaysOnBottom ? Qt.WindowStaysOnBottomHint : 0) | (Settings.frameless ? Qt.FramelessWindowHint : 0)
 	title: Stdin.closed ? "Blobdrop" : "Reading from stdin..."
 	width: 400
 	height: Math.max(48, Math.min(800, pathView.count ? pathView.contentHeight + 2 * pathView.anchors.topMargin : 350))