Improve system3.ini parser

- keys are case-insensitive
- spaces are allowed in values

src/config.cpp

@@ -1,6 +1,8 @@
 #include "config.h"
 
 #include "common.h"
+#include <tuple>
+#include <utility>
 #include <stdio.h>
 #include <string.h>
 #ifdef _WIN32
@@ -32,6 +34,25 @@ bool is_empty_line(const char *s)
 	return true;
 }
 
+char *trim(char *s)
+{
+	while (isspace(*s))
+		s++;
+	char *p = s + strlen(s) - 1;
+	while (p > s && isspace(*p))
+		*p-- = '\0';
+	return s;
+}
+
+std::pair<char*, char*> parse_keyval(char *line)
+{
+	char *eq = strchr(line, '=');
+	if (!eq)
+		return {nullptr, nullptr};
+	*eq = '\0';
+	return { trim(line), trim(eq + 1) };
+}
+
 }  // namespace
 
 Config::Config(int argc, char *argv[])
@@ -89,22 +110,28 @@ void Config::load_ini()
 			else
 				WARNING(INIFILENAME ":%d Unknown section \"%s\"", lineno, val);
 		} else if (current_section == CONFIG) {
-			if (sscanf(line, "noantialias = %s", val))
-				no_antialias = to_bool(val, lineno);
-			else if (sscanf(line, "savedir = %s", val))
-				save_dir = val;
-			else if (sscanf(line, "fontfile = %s", val))
-				font_file = val;
-			else if (sscanf(line, "playlist = %s", val))
-				playlist = val;
-			else if (sscanf(line, "fm = %s", val))
-				use_fm = to_bool(val, lineno);
-			else if (sscanf(line, "game = %s", val))
-				game_id = val;
-			else if (sscanf(line, "encoding = %s", val))
-				encoding = val;
-			else if (!is_empty_line(line))
+			char *key, *val;
+			std::tie(key, val) = parse_keyval(line);
+			if (!key && !is_empty_line(line)) {
 				WARNING(INIFILENAME ":%d parse error", lineno);
+				continue;
+			}
+			if (!strcasecmp(key, "noantialias"))
+				no_antialias = to_bool(val, lineno);
+			else if (!strcasecmp(key, "savedir"))
+				save_dir = val;
+			else if (!strcasecmp(key, "fontfile"))
+				font_file = val;
+			else if (!strcasecmp(key, "playlist"))
+				playlist = val;
+			else if (!strcasecmp(key, "fm"))
+				use_fm = to_bool(val, lineno);
+			else if (!strcasecmp(key, "game"))
+				game_id = val;
+			else if (!strcasecmp(key, "encoding"))
+				encoding = val;
+			else
+				WARNING(INIFILENAME ":%d unknown key '%s'", lineno, key);
 		} else if (!is_empty_line(line)) {
 			WARNING(INIFILENAME ":%d parse error", lineno);
 		}