Add /names, Ctrl-P/N scrollback, charset logger, terminal fixes

- /names #channel to list users
- Ctrl-P/Ctrl-N for page up/down in scrollback
- Charset logger (irc.log) with hex dump and detection
- chartest.c utility for inspecting key codes
- Fix window redraw to align lines at bottom
- Fix terminal cleanup via atexit (no more broken terminal)
- Green prompt

chartest.c

@@ -0,0 +1,32 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <termios.h>
+
+int main(void)
+{
+	struct termios orig, raw;
+	tcgetattr(STDIN_FILENO, &orig);
+	raw = orig;
+	raw.c_lflag &= ~(ICANON | ECHO);
+	raw.c_cc[VMIN] = 1;
+	tcsetattr(STDIN_FILENO, TCSANOW, &raw);
+
+	printf("Press keys (Ctrl-D to quit):\n");
+	for (;;) {
+		unsigned char c;
+		if (read(STDIN_FILENO, &c, 1) <= 0 || c == 0x04)
+			break;
+		printf("  dec=%3d  hex=0x%02X  oct=%03o", c, c, c);
+		if (c >= 32 && c < 127)
+			printf("  char='%c'", c);
+		else if (c >= 0xC0)
+			printf("  (UTF-8 lead byte, %d-byte seq)",
+			       c < 0xE0 ? 2 : c < 0xF0 ? 3 : 4);
+		else if ((c & 0xC0) == 0x80)
+			printf("  (UTF-8 continuation)");
+		printf("\n");
+	}
+
+	tcsetattr(STDIN_FILENO, TCSANOW, &orig);
+	return 0;
+}