simulator: replace gpssim with simple orb publication

- this is one of the last pieces of the system that still depend on DriverFramework
 - add new SIM_GPS_NOISE_X parameter for optionally increasing the GPS noise multiplier (was previously a gpssim command line option)
 - add SIM_x_BLOCK parameters to block sensor publication
   - SIM_GPS_BLOCK
   - SIM_ACCEL_BLOCK
   - SIM_GYRO_BLOCK
   - SIM_MAG_BLOCK
   - SIM_BARO_BLOCK
   - SIM_DPRES_BLOCK

src/modules/simulator/simulator.cpp

@@ -47,27 +47,10 @@
 
 #include "simulator.h"
 
-using namespace simulator;
-
 static px4_task_t g_sim_task = -1;
 
 Simulator *Simulator::_instance = nullptr;
 
-Simulator *Simulator::getInstance()
-{
-	return _instance;
-}
-
-bool Simulator::getGPSSample(uint8_t *buf, int len)
-{
-	return _gps.copyData(buf, len);
-}
-
-void Simulator::write_gps_data(void *buf)
-{
-	_gps.writeData(buf);
-}
-
 void Simulator::parameters_update(bool force)
 {
 	// check for parameter updates
@@ -107,16 +90,6 @@ int Simulator::start(int argc, char *argv[])
 	}
 }
 
-void Simulator::set_ip(InternetProtocol ip)
-{
-	_ip = ip;
-}
-
-void Simulator::set_port(unsigned port)
-{
-	_port = port;
-}
-
 static void usage()
 {
 	PX4_INFO("Usage: simulator {start -[spt] [-u udp_port / -c tcp_port] |stop}");