param: refactor BlockParam classes

- make the selected parameter a template argument. This
  enables type-checking at compile-time.
- move things to src/platforms.
  This provides consistent includes with ModuleBase
- add ModuleParams base class (replaces Block & SuperBlock)
- drop the Block* prefix from the class names

src/modules/systemlib/param/param.c

@@ -824,6 +824,11 @@ param_used(param_t param)
 	       (1 << param_index % bits_per_allocation_unit);
 }
 
+void param_set_used(param_t param)
+{
+	param_set_used_internal(param);
+}
+
 void param_set_used_internal(param_t param)
 {
 	int param_index = param_get_index(param);

src/modules/systemlib/param/param.h

@@ -252,6 +252,14 @@ __EXPORT int		param_get(param_t param, void *val);
  */
 __EXPORT int		param_set(param_t param, const void *val);
 
+/**
+ * Mark a parameter as used. Only marked parameters will be sent to a GCS.
+ * A call to param_find() will mark a param as used as well.
+ *
+ * @param param		A handle returned by param_find or passed by param_foreach.
+ */
+__EXPORT void		param_set_used(param_t param);
+
 /**
  * Set the value of a parameter, but do not notify the system about the change.
  *
@@ -488,6 +496,7 @@ static inline int param_get_cplusplus(param_t param, int32_t *val)
 
 #define param_get(param, val) param_get_cplusplus(param, val)
 
+
 #endif /* __cplusplus */
 
 #endif

src/modules/systemlib/param/param_shmem.c

@@ -805,6 +805,11 @@ param_used(param_t param)
 	       (1 << param_index % bits_per_allocation_unit);
 }
 
+void param_set_used(param_t param)
+{
+	param_set_used_internal(param);
+}
+
 void param_set_used_internal(param_t param)
 {
 	int param_index = param_get_index(param);

src/modules/systemlib/param/templates/px4_parameters_public.h.jinja

@@ -13,7 +13,7 @@ namespace px4 { {# wrap the enum in a namespace, otherwise we get shadowing erro
 /// Enum with all parameters
 enum class params {
 	{# enums are guaranteed to start with 0 (if the value for the first is not
-	   specified), and then incremented by 1 #}
+	   specified), and then incremented by 1 (the implementation depends on that!)  #}
 {%- for param in params %}
 	{{ param.attrib["name"] }},
 {%- endfor %}