linkManagement returns no value

[wystewart]

linkManagement returns no value. this hangs STM32 Arduino.

Suggest to change return to void, since it seems unused.

Also SvgParser::getPropertyStart returns no value on success.
SvgParser::callbackManagement returns no value on success or fail.
SvgParser::parseInCallbacks returns no value on success

[maxpautsch]

are this all changes necessary? unfortunately, I have not STM32 board to test. if yes, I would make the changes and increment the arduino lib version