Move panic handler and gdbstub into esp32 component, clean up wdt according to merge req suggestions

components/esp32/include/esp_int_wdt.h

@@ -23,15 +23,29 @@ extern "C" {
   * @{
   */
 
+/*
+This routine enables a watchdog to catch instances of processes disabling
+interrupts for too long, or code within interrupt handlers taking too long. 
+It does this by setting up a watchdog which gets fed from the FreeRTOS
+task switch interrupt. When this watchdog times out, initially it will call
+a high-level interrupt routine that will panic FreeRTOS in order to allow
+for forensic examination of the state of the CPU. When this interrupt 
+handler is not called and the watchdog times out a second time, it will 
+reset the SoC.
+
+This uses the TIMERG1 WDT.
+*/
+
+
 /**
-  * @brief  Initialize the interrupt watchdog. This is called in the init code, no need to 
-  *         call it explicitly.
+  * @brief  Initialize the interrupt watchdog. This is called in the init code if
+  *         the interrupt watchdog is enabled in menuconfig.
   *
   * @param  null
   *
   * @return null
   */
-void int_wdt_init();
+void esp_int_wdt_init();
 
 
 /**