feat(Eve-O-Preview): add hotkey to toggle all thumbnails and update target framework

src/Eve-O-Preview/Configuration/Implementation/ThumbnailConfiguration.cs

@@ -124,6 +124,8 @@ namespace EveOPreview.Configuration.Implementation {
             this.IconName = "";
 
             this.LoginThumbnailLocation = new Point(5, 5);
+            this.ToggleAllThumbnailsHotkey = "Alt+F12";
+            this.ThumbnailsManuallyHidden = false;
         }
 
         [JsonProperty("ConfigVersion")]
@@ -318,6 +320,16 @@ namespace EveOPreview.Configuration.Implementation {
             get; set;
         }
 
+        [JsonProperty("ToggleAllThumbnailsHotkey")]
+        public string ToggleAllThumbnailsHotkey {
+            get; set;
+        }
+
+        [JsonProperty("ThumbnailsManuallyHidden")]
+        public bool ThumbnailsManuallyHidden {
+            get; set;
+        }
+
         [JsonProperty]
         private Dictionary<string, Dictionary<string, Point>> PerClientLayout {
             get; set;