fix multithread logic in template app, update gpio HAL (#250)

* fix multithread logic
* more buffer for dallas id string
* update apps to use new logic
* delay_us small speedup
* add consant qualifier to gpio records and some core api
* fix some apps to use simpler method of getting gpio record
* fix ibutton app, stupid stack problem

applications/backlight-control/backlight-control.c

@@ -7,11 +7,8 @@ static void event_cb(const void* value, void* ctx) {
 const uint32_t BACKLIGHT_TIME = 10000;
 
 void backlight_control(void* p) {
-    // create pin
-    GpioPin backlight = backlight_gpio;
-
     // TODO open record
-    GpioPin* backlight_record = &backlight;
+    const GpioPin* backlight_record = &backlight_gpio;
 
     // configure pin
     gpio_init(backlight_record, GpioModeOutputPushPull);