Rename USART module to UART to emphasize asynchronous mode operation

src/main.c

@@ -1,5 +1,5 @@
 #include "common.h"
-#include "bus/usart.h"
+#include "bus/uart.h"
 #include "bus/mosfet.h"
 #include "bus/pwm.h"
 #include "bus/i2c.h"
@@ -52,7 +52,7 @@ static int Init(void)
 	// IRQs, so we need to initialize it as soon as
 	// possible and make sure to enable interrupts.
 
-	USART_Init();
+	UART_Init();
 	sei();
 
 	Info("Initializing...");
@@ -134,7 +134,7 @@ static void Update(void)
 	cmd_t cmd;
 
 	// Parse serial commands
-	while ((ch = USART_Getc()) >= 0) {
+	while ((ch = UART_Getc()) >= 0) {
 		if (!CMD_Parse(ch, &cmd)) {
 			continue;
 		}