turn on -Werror and fix resulting errors

src/modules/attitude_estimator_so3/attitude_estimator_so3_main.cpp

@@ -153,7 +153,7 @@ int attitude_estimator_so3_main(int argc, char *argv[])
 					      SCHED_PRIORITY_MAX - 5,
 					      14000,
 					      attitude_estimator_so3_thread_main,
-					      (argv) ? (const char **)&argv[2] : (const char **)NULL);
+					      (argv) ? (char * const *)&argv[2] : (char * const *)NULL);
 		exit(0);
 	}
 

src/modules/attitude_estimator_so3/module.mk

@@ -8,3 +8,5 @@ SRCS		 = attitude_estimator_so3_main.cpp \
 		   attitude_estimator_so3_params.c
 
 MODULE_STACKSIZE = 1200
+
+EXTRACXXFLAGS = -Wno-float-equal