My code is Arduinoish. I turned on verbose compiling so I could verify that all the .o files are indeed getting passed to the linker correctly, and they are (linker command
You need to create memory and initialize your static variables.
In your CPP file add the following:
NewSoftSerial SerialServoControl::_serial(9, 8); char SerialServoControl::_tx = 0; char SerialServoControl::_rx = 0;