Add control-panel builders

I've used these in a few projects now, so might as well put them in a
common library where they can get properly enhanced.

src/main/scala/org/gerweck/scalafx/util/control/ControlPanel.scala

@@ -0,0 +1,83 @@
+package org.gerweck.scalafx.util.control
+
+import language.implicitConversions
+
+import scalafx.geometry.Orientation.Horizontal
+import scalafx.geometry.Pos
+import scalafx.scene.Node
+import scalafx.scene.control.{ Label, Separator }
+import scalafx.scene.layout._
+import scalafx.scene.text._
+
+import org.gerweck.scalafx.util._
+
+import ControlPanel._
+
+object HorizontalControlPanel {
+  def apply(controls: ControlPanelEntry*): Pane =
+    new HBox {
+      alignment = Pos.Center
+      hgrow = Priority.Always
+      spacing = 15
+      children = controls map {
+        case RegularControl(name, control) =>
+          new HBox {
+            spacing = 4
+            hgrow = Priority.Always
+            children = ControlPanel.controlRow(name, control)
+            alignment = Pos.CenterRight
+          }
+        case SeparatorEntry =>
+          Separators.vertical
+      }
+    }
+}
+
+object VerticalControlPanel {
+  def apply(controls: ControlPanelEntry*): Pane = new GridPane { gp =>
+    hgap = 4
+    vgap = 6
+    for ((entry, i) <- controls.zipWithIndex) {
+      entry match {
+        case RegularControl(name, control) =>
+          gp.addToRow(i, ControlPanel.controlRow(name, control): _*)
+
+        case SeparatorEntry =>
+          val sep = new Separator {
+            orientation = Horizontal
+          }
+          gp.add(sep, 0, i, 2, 1)
+      }
+    }
+  }
+}
+
+object ControlPanel {
+  def apply(controls: ControlPanelEntry*): Pane = VerticalControlPanel(controls: _*)
+
+  private[this] lazy val defaultFont = new Font(Font.default)
+  private[this] lazy val boldFont = {
+    Font(defaultFont.family, FontWeight.Bold, defaultFont.size)
+  }
+
+  private[this] lazy val labelsFont = defaultFont
+
+  private[control] def controlRow(name: String, control: Node) = {
+    val label = new Label(name + ':') {
+      alignmentInParent = Pos.CenterRight
+      font = labelsFont
+    }
+    Seq(label, control)
+  }
+
+  /* It's expected that you won't create these directly, but that you'll
+   * mostly use the implicit magnets */
+  sealed trait ControlPanelEntry
+  case class RegularControl(label: String, control: Node) extends ControlPanelEntry
+  case object SeparatorEntry extends ControlPanelEntry
+
+  object ControlPanelEntry {
+    implicit def pair2Regular(p: (String, Node)): RegularControl = RegularControl.tupled(p)
+    implicit def sep2Sep(p: Separator): SeparatorEntry.type = SeparatorEntry
+  }
+}