Actually use RAM vector table!

teensy3/mk20dx128.c

 	while (dest < &_edata) *dest++ = *src++;
 	dest = &_sbss;
 	while (dest < &_ebss) *dest++ = 0;
-	SCB_VTOR = 0;	// use vector table in flash
 
 	// default all interrupts to medium priority level
 	for (i=0; i < NVIC_NUM_INTERRUPTS + 16; i++) _VectorsRam[i] = _VectorsFlash[i];
 	for (i=0; i < NVIC_NUM_INTERRUPTS; i++) NVIC_SET_PRIORITY(i, 128);
+	SCB_VTOR = (uint32_t)_VectorsRam;	// use vector table in RAM
 
 	// hardware always starts in FEI mode
 	//  C1[CLKS] bits are written to 00