pyxcp/master/master.py the connect method cannot be called more than once

[nedlukasz]

For now Master.connect method do two things setup transport layer (transport.connect()) and also invoke XCP command connect but it will be really nice to have possibility to invoke only XCP command.

There can be for example bool argument setup_transport_layer:

def connect(self, mode=0x00, setup_transport_layer=True):
    if setup_transport_layer:
	    self.transport.connect()
    response = self.transport.request(types.Command.CONNECT, mode & 0xFF)