Major restructure

kern/libkern/uart.c

@@ -0,0 +1,8 @@
+/* QEMU memory maps a UART device here. */
+#define UART_BASE ((volatile char *)0x10000000)
+
+void uart_putc(char c) { *UART_BASE = c; }
+
+void uart_puts(const char *s) {
+    while (*s) uart_putc(*s++);
+}