Adding initial Teensy 3 support, compiles, but not fully functional yet.

- CDC Output seems to be working
- USB Keyboard output has not been tested, but is "ready"
- UART and Timers have not been tested, or fully utilized
- Issues using Timer 0
- Initial template for MBC-55X Scan module (only module currently compatible with the arm build)
- Updated the interface to the AVR usb module for symmetry with the ARM usb module
- Much gutting was done to the Teensy 3 usb keyboard module, though not in an ideal state yet

USB/pjrc/arm/usb_dev.h

@@ -0,0 +1,38 @@
+#ifndef _usb_dev_h_
+#define _usb_dev_h_
+
+// This header is NOT meant to be included when compiling
+// user sketches in Arduino.  The low-level functions
+// provided by usb_dev.c are meant to be called only by
+// code which provides higher-level interfaces to the user.
+
+#include "usb_mem.h"
+#include "usb_desc.h"
+
+void usb_init(void);
+uint8_t usb_configured(void);		// is the USB port configured
+void usb_isr(void);
+usb_packet_t *usb_rx(uint32_t endpoint);
+uint32_t usb_rx_byte_count(uint32_t endpoint);
+uint32_t usb_tx_byte_count(uint32_t endpoint);
+uint32_t usb_tx_packet_count(uint32_t endpoint);
+void usb_tx(uint32_t endpoint, usb_packet_t *packet);
+void usb_tx_isr(uint32_t endpoint, usb_packet_t *packet);
+
+extern volatile uint8_t usb_configuration;
+
+#ifdef CDC_DATA_INTERFACE
+extern uint8_t usb_cdc_line_coding[7];
+extern volatile uint8_t usb_cdc_line_rtsdtr;
+extern volatile uint8_t usb_cdc_transmit_flush_timer;
+extern void usb_serial_flush_callback(void);
+#endif
+
+#ifdef SEREMU_INTERFACE
+extern volatile uint8_t usb_seremu_transmit_flush_timer;
+extern void usb_seremu_flush_callback(void);
+#endif
+
+
+#endif
+