Clean up of app.h

app.h, generated from app.h_in, has unnecessary code duplication
and isn't a header file (it defines globals, static functions
and doesn't have a header guard, moreover, it has a 'using namespace
std;'). Because of this, a real headerfile that declares the stuff
defined in apps.h was missing leading to even more code duplication:
scattered forward declarations in .cpp files and an often repeated
type of std::map<std::string, px4_main_t>.

This patch moves cmake/qurt/apps.h_in to src/platforms/apps.cpp.in
(with some changes) and removes cmake/posix/apps.h_in.
Then src/platforms/apps.cpp.in is split into src/platforms/apps.cpp.in
and src/platforms/apps.h.in, splitting declarations from definitions.

A typedef is defined for the map (apps_map_type).

The main difference between cmake/posix/apps.h_in and
cmake/qurt/apps.h_in was that the first defined a global 'apps',
while qurt stores the apps in QShell. I opted to get rid of
the global variable (which are in general evil for various reasons)
and used the API of cmake/qurt/apps.h_in where a provided 'apps'
map is initialized with a call to init_app_map. Thus removing
the existing code duplication.

src/platforms/apps.cpp.in

@@ -0,0 +1,74 @@
+/* definitions of builtin command list - automatically generated, do not edit */
+#include "px4_posix.h"
+#include "px4_log.h"
+
+#include "apps.h"
+
+#include <iostream>
+#include <map>
+#include <string>
+
+#include <cstdlib>
+
+extern void px4_show_devices(void);
+
+void init_app_map(apps_map_type &apps)
+{
+${builtin_apps_string}
+	apps["shutdown"] = shutdown_main;
+	apps["list_tasks"] = list_tasks_main;
+	apps["list_files"] = list_files_main;
+	apps["list_devices"] = list_devices_main;
+	apps["list_topics"] = list_topics_main;
+	apps["sleep"] = sleep_main;
+}
+
+void list_builtins(apps_map_type &apps)
+{
+	PX4_INFO("Builtin Commands:\n");
+	for (apps_map_type::iterator it = apps.begin(); it != apps.end(); ++it)
+		PX4_INFO("%s : 0x%x\n", it->first.c_str(), it->second);
+}
+
+int shutdown_main(int argc, char *argv[])
+{
+	std::cout << "Shutting down" << std::endl;
+	exit(0);
+}
+
+int list_tasks_main(int argc, char *argv[])
+{
+	px4_show_tasks();
+	return 0;
+}
+
+int list_devices_main(int argc, char *argv[])
+{
+	px4_show_devices();
+	return 0;
+}
+
+int list_topics_main(int argc, char *argv[])
+{
+	px4_show_topics();
+	return 0;
+}
+
+int list_files_main(int argc, char *argv[])
+{
+	px4_show_files();
+	return 0;
+}
+
+int sleep_main(int argc, char *argv[])
+{
+        if (argc != 2) {
+           PX4_WARN( "Usage: sleep <seconds>" );
+           return 1;
+        }
+
+        unsigned long usecs = 1000000UL * atol(argv[1]);
+        std::cout << "Sleeping for " << argv[1] << " s; (" << usecs << " us)." << std::endl;
+        usleep(usecs);
+        return 0;
+}