Merge pull request #2839 from mrfabbri/fix-tray-icon-title-osx

Fix tray title/tooltip issues on Mac OS X
Update fix tray title issue

- Update the fix on tray title when the title is given as an option in `Tray`
item creation (postponing the call to `SetTitle` during `Tray` item initialisation).

- `NSMenuItem setTitle` [should be and] is called always twice to the
dimensions of the text label right.
Add automatic tests for Tray item