Bugfixes and cleanups for the third robot.

- Fix a bug in the gyro board code that would cause it to
enable the ISR for the wrong timer.
- Fix a bug in the gyro board code that would cause it to
set a falling edge interrupts on the wrong pin.
- Cleanup some junk in gyp files.
- Break usb_receiver stuff into a separate gyp file so it would
build correctly for both robots.
- Fix the dip switch numbering in the gyro board code.
diff --git a/gyro_board/src/usb/digital.c b/gyro_board/src/usb/digital.c
index 83ef169..ed8522a 100644
--- a/gyro_board/src/usb/digital.c
+++ b/gyro_board/src/usb/digital.c
@@ -30,7 +30,7 @@
 
 int is_bot3;
 void digital_init(void) {
-  if (dip_switch(0) || dip_switch(1) || dip_switch(2) || dip_switch(3)) {
+  if (dip_switch(1) || dip_switch(2) || dip_switch(3) || dip_switch(4)) {
     is_bot3 = 1;
   } else {
     is_bot3 = 0;