Add unicode character table for font subsetting

tools/Makefile

@@ -0,0 +1,5 @@
+uchars.txt: uchars
+	./uchars > $@
+
+uchars: uchars.c
+	gcc -o $@ $<

tools/uchars.c

@@ -0,0 +1,37 @@
+#include <stdio.h>
+#include "../src/s2utbl.h"
+
+void print_utf8(int code) {
+	if (code <= 0x7f) {
+		putchar(code);
+	} else if (code <= 0x7ff) {
+		putchar(0xc0 | code >> 6);
+		putchar(0x80 | (code & 0x3f));
+	} else {
+		putchar(0xe0 | code >> 12);
+		putchar(0x80 | (code >> 6 & 0x3f));
+		putchar(0x80 | (code & 0x3f));
+	}
+}
+
+int main() {
+	// ASCII
+	for (int c = ' '; c <= '~'; c++)
+		putchar(c);
+	putchar('\n');
+
+	// Half-width kana
+	for (int c = 0xff61; c <= 0xff9f; c++)
+		print_utf8(c);
+	putchar('\n');
+
+	for (int hi = 0; hi < 0x80; hi++) {
+		for (int lo = 0; lo < 0xc0; lo++) {
+			int code = s2u[hi][lo];
+			if (code == 0x30fb && !(hi == 0x01 && lo == 0x05))
+				continue;
+			print_utf8(code);
+			putchar('\n');
+		}
+	}
+}