integrated serial mouse drivers as a feature into the firmware architecture

* can be enabled by defining Makefile macro SERIAL_MOUSE_MICROSOFT_ENABLE or
   SERIAL_MOUSE_MOUSESYSTEMS_ENABLE.
 * Serial implementation can be chosen via SERIAL_MOUSE_USE_SOFT and
   SERIAL_MOUSE_USE_UART macros
 * UART configuration still has to be done in config.h: I added working clauses
   for both mouse protocols to ps2_usb's config.h

protocol/lufa/lufa.c

@@ -49,6 +49,10 @@
 #endif
 #include "suspend.h"
 
+#ifdef SERIAL_MOUSE_ENABLE
+#include "serial_mouse.h"
+#endif
+
 #include "descriptor.h"
 #include "lufa.h"
 
@@ -571,6 +575,10 @@ int main(void)
     sleep_led_init();
 #endif
 
+#ifdef SERIAL_MOUSE_ENABLE
+    serial_mouse_init();
+#endif
+
     print("Keyboard start.\n");
     while (1) {
         while (USB_DeviceState == DEVICE_STATE_Suspended) {
@@ -582,6 +590,10 @@ int main(void)
 
         keyboard_task();
 
+#ifdef SERIAL_MOUSE_ENABLE
+        serial_mouse_task();
+#endif
+
 #if !defined(INTERRUPT_CONTROL_ENDPOINT)
         USB_USBTask();
 #endif

protocol/serial_mouse_mousesystems.c

@@ -27,7 +27,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "print.h"
 #include "debug.h"
 
-#define SERIAL_MOUSE_CENTER_SCROLL
+//#define SERIAL_MOUSE_CENTER_SCROLL
 
 static void print_usb_data(const report_mouse_t *report);