[OSX] Allow usage of CommandLineParser.java without showing splashscreen

[jpmckearin]

microsoft/vscode-arduino#453

It seems like using the command line for external actions (not in the IDE) should not open a splashscreen in OSX. This splashscreen causes the 3rd party application to lose focus which can be quite annoying when using spaces in OSX.

[facchinm]

Hi @jpmckearin ,
the problem is that the splash is handled by the laucher (launch4j) and not by Arduino itself, so we have no control if it should be displayed or not (on OSX). As a workaround, launching pde.jar directly does not show the splash.
However, every PR is accepted (as per Help wanted tag on #1970)

[jpmckearin]

It looks like someone else already got around to this. I must have missed it when searching. Thanks for the help @facchinm
microsoft/vscode-arduino#451