Save layer visibility

Sources/arm/ProjectFormat.hx

@@ -30,6 +30,7 @@ typedef TLayerData = {
 	public var object_mask: Int;
 	public var blending: Int;
 	public var parent: Int;
+	public var visible: Bool;
 	public var paint_base: Bool;
 	public var paint_opac: Bool;
 	public var paint_occ: Bool;

Sources/arm/io/ExportArm.hx

@@ -60,6 +60,7 @@ class ExportArm {
 				object_mask: l.objectMask,
 				blending: l.blending,
 				parent: l.parent != null ? Project.layers.indexOf(l.parent) : -1,
+				visible: l.visible,
 				paint_base: l.paintBase,
 				paint_opac: l.paintOpac,
 				paint_occ: l.paintOcc,

Sources/arm/io/ImportArm.hx

@@ -266,7 +266,7 @@ class ImportArm {
 					l.material_mask = ld.material_mask > -1 ? Project.materials[ld.material_mask] : null;
 					l.objectMask = ld.object_mask;
 					l.blending = ld.blending;
-
+					l.visible = ld.visible;
 					l.paintBase = ld.paint_base;
 					l.paintOpac = ld.paint_opac;
 					l.paintOcc = ld.paint_occ;