Storing scene view settings

[madsendennis]

Implementation of the possibility to store scene view settings.
Mainly:

• Camera settings
• Slicing positions
• Window size
  This would make it easier to recreate exact screenshots.

Other possibilities would also be to store:

• Level, window and opacity of 3D images
• Opacity and color of meshes and landmarks

The settings can be saved to and loaded from a config file which also enables sharing of scene view settings.

[clangguth]

Window size and perspective should already be saved and restored when exiting/reopening the application:

scalismo-ui/src/main/scala/scalismo/ui/view/ScalismoFrame.scala

Lines 157 to 175 in c600875

	protected def saveWindowState(): Unit = {
	GlobalSettings.set(GlobalSettings.Keys.WindowMaximized, maximized)
	if (!maximized) {
	// Saving width/height in maximized state is pointless. It should have been done *before*
	// the window was maximized (see the maximize() method)
	saveWindowWidthHeight()
	}
	}
	protected def restoreWindowState(): Unit = {
	val width = GlobalSettings.get[Int](GlobalSettings.Keys.WindowWidth).getOrElse(1024)
	val height = GlobalSettings.get[Int](GlobalSettings.Keys.WindowHeight).getOrElse(768)
	size = new Dimension(width, height)
	centerOnScreen()
	if (GlobalSettings.get[Boolean](GlobalSettings.Keys.WindowMaximized).getOrElse(false)) {
	maximize()
	}
	}

So all the basics are already there (package settings), it's just a matter of controlling what to save/restore and how. I'd suggest reusing that base, just using a different file (possibly user-selectable), not the global settings one.