UrDriver: Send program in headless mode after creating trajectory and script_command servers (#271)

Before, we were sending the script code for execution to the robot and
then opening the sockets that the script would connect to.

This has been working fine in most cases, but that fails when too much
time passes between the two steps. E.g. I experienced that when having
debug output switched on, the robot script was not able to connect to
the sockets.

From my understanding this has been overlooked and there is no specific
reason why the order was like that. Opening the sockets first and then
sending the script seems to make more sense.

Author: urfeex

src/ur/ur_driver.cpp

@@ -148,6 +148,9 @@ void UrDriver::init(const UrDriverConfiguration& config)
   }
   prog.replace(prog.find(BEGIN_REPLACE), BEGIN_REPLACE.length(), begin_replace.str());
 
+  trajectory_interface_.reset(new control::TrajectoryPointInterface(config.trajectory_port));
+  script_command_interface_.reset(new control::ScriptCommandInterface(config.script_command_port));
+
   if (in_headless_mode_)
   {
     full_robot_program_ = "stop program\n";
@@ -167,9 +170,6 @@ void UrDriver::init(const UrDriverConfiguration& config)
     URCL_LOG_DEBUG("Created script sender");
   }
 
-  trajectory_interface_.reset(new control::TrajectoryPointInterface(config.trajectory_port));
-  script_command_interface_.reset(new control::ScriptCommandInterface(config.script_command_port));
-
   if (!std::empty(config.calibration_checksum))
   {
     URCL_LOG_WARN("DEPRECATION NOTICE: Passing the calibration_checksum to the UrDriver's constructor has been "