Desktop integration (#2073)

* Open stash in system tray on Windows/MacOS
* Add desktop notifications
* MacOS Bundling
* Add binary icon

Co-authored-by: WithoutPants <53250216+WithoutPants@users.noreply.github.com>

vendor/github.com/go-toast/toast/readme.md

@@ -0,0 +1,61 @@
+# Toast
+
+A go package for Windows 10 toast notifications.
+
+As seen in [jacobmarshall/pokevision-cli](https://github.com/jacobmarshall/pokevision-cli).
+
+## CLI
+
+As well as using go-toast within your Go projects, you can also utilise the CLI - for any of your projects.
+
+Download [64bit](https://go-toast-downloads.s3.amazonaws.com/v1/toast64.exe) or [32bit](https://go-toast-downloads.s3.amazonaws.com/v1/toast32.exe)
+
+```cmd
+C:\Users\Example\Downloads\toast64.exe \
+  --app-id "Example App" \
+  --title "Hello World" \
+  --message "Lorem ipsum dolor sit amet, consectetur adipiscing elit." \
+  --icon "C:\Users\Example\Pictures\icon.png" \
+  --audio "default" --loop \
+  --duration "long" \
+  --activation-arg "https://google.com" \
+  --action "Open maps" --action-arg "bingmaps:?q=sushi" \
+  --action "Open browser" --action-arg "http://..."
+```
+
+![CLI](./screenshot-cli.png)
+
+## Example
+
+```go
+package main
+
+import (
+    "log"
+
+    "gopkg.in/toast.v1"
+)
+
+func main() {
+    notification := toast.Notification{
+        AppID: "Example App",
+        Title: "My notification",
+        Message: "Some message about how important something is...",
+        Icon: "go.png", // This file must exist (remove this line if it doesn't)
+        Actions: []toast.Action{
+            {"protocol", "I'm a button", ""},
+            {"protocol", "Me too!", ""},
+        },
+    }
+    err := notification.Push()
+    if err != nil {
+        log.Fatalln(err)
+    }
+}
+```
+
+## Screenshots
+
+![Toast](./screenshot-toast.png)
+
+![Action centre](./screenshot-action-centre.png)