Fix comment: the word "no-op" needs to be split

The tilde may be escaped, and this first escape may be escaped
as well, so all paths should be expressable.

All will just work(TM) for those who need it, and those who start
filenames with backslashes are begging to have their foot shot.

It appears that even Shift JIS, Big5, GB 18030, and GBK are
compatible with Unix paths, meaning they don't redefine the slash
(0x2F), so I'm okay with my direct multibyte string handling in
unknown locales.

Legacy stuff smells.

sdn.cpp

@@ -113,6 +113,28 @@ fun split (const string &s, const string &sep) -> vector<string> {
 	vector<string> result; split (s, sep, result); return result;
 }
 
+fun untilde (const string &path) -> string {
+	if (path.empty ())
+		return path;
+
+	string tail = path.substr (1);
+	if (path[0] == '\\')
+		return tail;
+	if (path[1] != '~')
+		return path;
+
+	// If there is something between the ~ and the first / (or the EOS)
+	if (size_t until_slash = tail.find ('/')) {
+		if (const auto *pw = getpwnam (tail.substr (0, until_slash).c_str ()))
+			return pw->pw_dir + tail.substr (until_slash);
+	} else if (const auto *home = getenv ("HOME")) {
+		return home + tail;
+	} else if (const auto *pw = getpwuid (getuid ())) {
+		return pw->pw_dir + tail;
+	}
+	return path;
+}
+
 fun needs_shell_quoting (const string &v) -> bool {
 	// IEEE Std 1003.1 sh + the exclamation mark because of csh/bash
 	// history expansion, implicitly also the NUL character
@@ -140,7 +162,7 @@ fun parse_line (istream &is, vector<string> &out) -> bool {
 	enum {TAKE = 1 << 3, PUSH = 1 << 4, STOP = 1 << 5, ERROR = 1 << 6};
 	enum {TWOR = TAKE | WOR};
 
-	// We never transition back to the start state, so it can stay as a noop
+	// We never transition back to the start state, so it can stay as a no-op
 	static char table[STATES][7] = {
 	// state   EOF          SP, TAB     '     #     \     LF           default
 	/* STA */ {ERROR,       DEF,        QUO,  COM,  ESC,  STOP,        TWOR},
@@ -1223,7 +1245,7 @@ fun handle (wint_t c) -> bool {
 	case ACTION_CHDIR:
 		g.editor = L"chdir";
 		g.editor_on_confirm = [] {
-			change_dir (to_mb (g.editor_line));
+			change_dir (untilde (to_mb (g.editor_line)));
 		};
 		break;
 	case ACTION_PARENT:
@@ -1233,10 +1255,7 @@ fun handle (wint_t c) -> bool {
 		change_dir (g.start_dir);
 		break;
 	case ACTION_GO_HOME:
-		if (const auto *home = getenv ("HOME"))
-			change_dir (home);
-		else if (const auto *pw = getpwuid (getuid ()))
-			change_dir (pw->pw_dir);
+		change_dir (untilde ("~"));
 		break;
 
 	case ACTION_SEARCH: