[GUI] Don't log to console by default.
[GUI] Don't log to console by default.

Default `-printtoconsole` to false for the GUI. GUI programs should not
print to the console unnecessarily. For example, when launched by the
window manager, the output might end up in the X session log file,
resulting in duplicate logging. On Windows, it is pointless as well
because bitcoin-qt isn't a console application.

Darknet-Crypto/Darknet,PIVX-Project/PIVX,PIVX-Project/PIVX,Darknet-Crypto/Darknet,Darknet-Crypto/Darknet,Darknet-Crypto/Darknet,PIVX-Project/PIVX,PIVX-Project/PIVX,Darknet-Crypto/Darknet,PIVX-Project/PIVX,PIVX-Project/PIVX,PIVX-Project/PIVX,Darknet-Crypto/Darknet,PIVX-Project/PIVX,PIVX-Project/PIVX