Add Terminal

Terminal.md

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+Lemur has a built-in terminal for debugging. Games can write arbitrary text to it, by writing one byte at a time to address `0x02000030`. This address does nothing on hardware, but writing messages still takes precious CPU time, so be sure not to leave any log lines around in your final game.
+
+
+The terminal is available in the menu under Tools > Terminal. You can also pass the flag `--terminal` to the emulator to open it at startup.
+
+Below are some utility methods.
+```c
+volatile unsigned char* const STDOUT = (unsigned char*) 0x02000030;
+
+int putchar(int ch) {
+    *STDOUT = ch;
+    return ch;
+}
+
+int puts(const char *str) {
+    while (*str != 0) {
+        *STDOUT = *str;
+        str++;
+    }
+    *STDOUT = '\n';
+    return 0;
+}
+```