Use OS independent API for task creation/deletion

Calls to task_delete and task_spawn_cmd are now
px4_task_delete and px4_task_spawn_cmd respectively.

The px4_tasks.h header was added to the affected files
and incusions of nuttx/config.h were removed.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

src/modules/attitude_estimator_so3/attitude_estimator_so3_main.cpp

@@ -50,7 +50,7 @@
  *  [2] Euston, M.; Coote, P.; Mahony, R.; Jonghyuk Kim; Hamel, T., "A complementary filter for attitude estimation of a fixed-wing UAV," Intelligent Robots and Systems, 2008. IROS 2008. IEEE/RSJ International Conference on , vol., no., pp.340,345, 22-26 Sept. 2008
  */
 
-#include <nuttx/config.h>
+#include <px4_tasks.h>
 #include <unistd.h>
 #include <stdlib.h>
 #include <string.h>
@@ -132,7 +132,7 @@ usage(const char *reason)
  * Makefile does only apply to this management task.
  *
  * The actual stack size should be set in the call
- * to task_spawn_cmd().
+ * to px4_task_spawn_cmd().
  */
 int attitude_estimator_so3_main(int argc, char *argv[])
 {
@@ -149,7 +149,7 @@ int attitude_estimator_so3_main(int argc, char *argv[])
 		}
 
 		thread_should_exit = false;
-		attitude_estimator_so3_task = task_spawn_cmd("attitude_estimator_so3",
+		attitude_estimator_so3_task = px4_task_spawn_cmd("attitude_estimator_so3",
 					      SCHED_DEFAULT,
 					      SCHED_PRIORITY_MAX - 5,
 					      14000,