Revisit splash screen suppression on OSX

[ianfixes]

Feature Request

Prevent splash screen on OSX

I've found a workaround for this issue on macOS :

• Edit the plist in /Applications/Arduino.app/Contents and simply remove the xml tag <splash-scren ..>
• to avoid that is you are in full screen the Arduino app get the main focus you must create a simple script (in Contents/MacOS) like run-arduino.sh that contains the following line open -g ./Arduino

arduino/Arduino#1970 (comment)