Usb serial (#1648)

* enabled usb clock
* added usb stack to application
* fixed pll0usb clock setup
* implemented serial usb handshake
* implemented serial communication
* integrated chibios shell
* implemented device reset
* implemented enter dfu mode
* implemented hackrf mode command
* implemented flash command
* implemented memory manipulation
* implemented button control
* fixed mode change
* improved reset behavior
* implemented directory commands
* implemented file commands
* improved data communication
* refactorings

firmware/application/irq_controls.hpp

@@ -56,6 +56,7 @@ namespace control {
 namespace debug {
 
 uint8_t switches();
+void inject_switch(uint8_t);
 
 }  // namespace debug
 }  // namespace control